2010-10-12 18:24:17 +00:00
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Collection of Boot Sector Formats for ISO 9660 Images
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by Thomas Schmitt - mailto:scdbackup@gmx.net
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Libburnia project - mailto:libburn-hackers@pykix.org
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This information is collected from various sources. Some is backed by
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2010-10-14 15:26:56 +00:00
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specifications, some is just rumor which happens to work (maybe not even that).
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2010-11-01 15:05:47 +00:00
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Content
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2010-10-14 15:26:56 +00:00
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EL Torito CD booting, for PC-BIOS x86, PowerPC, (old) Mac, EFI.
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MBR, for PC-BIOS x86 from (pseudo-) hard disk
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2010-10-14 20:34:32 +00:00
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- SYSLINUX isohybrid MBR
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2012-05-06 08:08:21 +00:00
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>>> under construction: - SYSLINUX isohybrid for UEFI and x86 Mac
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- GRUB2 grub-mkrescue MBR
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2010-10-14 15:26:56 +00:00
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MIPS Volume Header, for MIPS Big Endian, e.g. SGI Indigo2.
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2010-10-12 18:24:17 +00:00
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2010-10-14 20:34:32 +00:00
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DEC Boot Block, for MIPS Little Endian , e.g. DECstation.
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2010-11-01 15:05:47 +00:00
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SUN Disk Label and boot images, for SUN SPARC
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2010-10-14 20:34:32 +00:00
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2010-10-12 18:24:17 +00:00
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------------------------------------------------------------------------------
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2010-10-14 20:34:32 +00:00
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2010-10-14 15:26:56 +00:00
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EL Torito CD booting
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for PC-BIOS x86, PowerPC, (old) Mac, EFI
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Sources:
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El Torito, Bootable CD-ROM Format Specification, Version 1.0, 1995
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which refers to ECMA-119, the standard for ISO 9660 filesystems.
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libisofs/eltorito.[ch] by Vreixo Formoso.
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man mkisofs by Joerg Schilling.
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ECMA-119 prescribes that the first 32 kB of an ISO 9660 image are System Area
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with arbitrary content. This prescription is obeyed by PC-BIOS systems only
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if the ISO 9660 image is presented on CD, DVD or BD media.
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In this case the El Torito Boot record is the starting point of booting.
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The Boot Record is a ECMA-119 Volume Descriptor which is eventually located
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at 2 kB block number 17 (decimal). Its content points to the location of the
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Boot Catalog.
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The format is described in part by ECMA-119 8.2 "Boot Record" and further
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specified by El Torito figure 7.
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Byte Range | Value | Meaning
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---------- | ---------- | ----------------------------------------------------
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0 - 0 | 0 | Volume Descriptor Type. 0= Boot record
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1 - 5 | "CD001" | Standard Identifier
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6 - 6 | 1 | Volume Descriptor Version
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7 - 38 | el_torito | Boot System Identifier
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39 - 70 | 0 | Boot Identifier
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71 -2047 | ========== | Boot System Use
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71 - 74 | cataloglba | The 2 kB block number of the Boot Catalog
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| | as little-endian 32 bit number.
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75 -2047 | 0 | Unused
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---------- | ---------- | ----------------------------------------------------
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el_torito is the constant string "EL TORITO SPECIFICATION" padded by 9 zeros.
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cataloglba has to be provided by the file system generator.
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The Boot Catalog lists the available boot images which may be prepared for
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multiple system architectures, called "platforms".
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It consists of one or more 2 kB blocks. The content is a sequence of fixed
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format entries, 32 bytes each.
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The entries are grouped in sections, which assign the entries to a particular
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system architecture. The booting system will then choose an entry from an
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appropriate section.
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Byte Range | Value | Meaning
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---------- | ---------- | ----------------------------------------------------
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0 - 31 | ========== | Validation Entry
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| | begins the first section, specifies an architecture
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32 - 63 | ========== | Initial/Default Entry
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| | points to a boot image for given architecture
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---------- | ---------- | ----------------------------------------------------
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Optional:
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---------- | ---------- | ----------------------------------------------------
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64 - 95 | ========== | Section Header entry
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| | begins new section, specifies an architecture
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96 - 127 | ========== | Section Entry
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| | points to a boot image for given architecture
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... | .......... | Optional more Section Entries
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... | .......... | Optional more Section Headers and their Section
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| | Entries
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---------- | ---------- | ----------------------------------------------------
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An architecture is refered by a Platform Id number.
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Defined by El Torito are:
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0 = "80x86" which is used for standard PCs with Intel x86 or compatible CPU
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1 = "PowerPC" (possibly for IBM machines with PowerPC CPU)
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2 = "Mac" (possibly for Apple computers with MC68000 or PowerPC CPU)
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2012-05-06 12:11:34 +00:00
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Further in use by GRUB2 and ISOLINUX is:
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2010-10-14 15:26:56 +00:00
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0xef = EFI, a competitor resp. successor to PC-BIOS, possibly in use with
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Intel ia64 Itanium and possibly with newer Apple machines.
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Words resp. numbers are represented are little-endian.
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Validation Entry:
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Byte Range | Value | Meaning
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---------- | ---------- | ----------------------------------------------------
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0 - 0 | 1 | Header Id
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1 - 1 | platform_id| Platform Id. One of: 0, 1, 2, 0xef. See above.
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2 - 3 | 0 | Reserved
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4 - 27 | manuf_dev | ID string identifies the manufacturer/developer
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| | (no non-zero examples known yet)
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28 - 29 | checksum | Checksum Word for the Validation Entry.
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| | The sum of all words in the entry has to be 0.
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30 - 30 | 0x55 |
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31 - 31 | 0xaa |
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---------- | ---------- | ----------------------------------------------------
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Initial/Default Entry:
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Byte Range | Value | Meaning
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---------- | ---------- | ----------------------------------------------------
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0 - 0 | boot_indct | Boot Indicator: 0x88 = bootable, 0x00 = not bootable
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1 - 1 | boot_media | Boot Media Type (i.e. media emulated by boot image):
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| | 0= no emulation , 1= 1.2 MB diskette, 2=1.44 MB,
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| | 3= 2.88 MB , 4= hard disk
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| | (About everybody uses 0 = no emulation)
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2 - 3 | load_seg | Load Segment. (meaning unclear)
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| | "If this value is 0 the system will use the
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| | traditional segment of 7C0."
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| | libisofs default is 0
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4 - 4 | sys_type | System Type.
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| | "Must be a copy of byte 5 from the partition table
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| | found in the boot image."
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| | libisofs reads the start the boot image as MBR
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| | if boot_media == 4. This emulated MBR has a
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| | partition table from where a byte gets copied.
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| | Else this byte is 0.
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5 - 5 | 0 | Unused
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6 - 7 | sec_count | Sector Count.
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| | "the number of virtual/emulated sectors the system
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| | will store at Load Segment during the initial boot
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| | procedure."
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2010-12-14 05:36:12 +00:00
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| | libisofs stores 1 for emulated boot_media and a
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| | user defined value for boot_media == 0. Often: 4.
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2010-10-14 15:26:56 +00:00
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8 - 11 | load_rba | Load RBA. The 2 kB block address where the boot
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| | image file content is located in the ISO 9660 image.
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12 - 31 | 0 | Unused
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---------- | ---------- | ----------------------------------------------------
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Section Header Entry:
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Byte Range | Value | Meaning
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---------- | ---------- | ----------------------------------------------------
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0 - 0 | head_ind | Header Indicator: 0x90 = more headers follow
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| | 0x91 = final header, last section
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1 - 1 | platform_id| Platform Id. One of: 0, 1, 2, 0xef. See above.
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2 - 3 | num_entries| Number of entries to follow in this section
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4 - 31 | | ID string identifies the manufacturer/developer
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---------- | ---------- | ----------------------------------------------------
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Section Entry:
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Byte Range | Value | Meaning
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---------- | ---------- | ----------------------------------------------------
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0 - 0 | boot_indct | Boot Indicator: 0x88 = bootable, 0x00 = not bootable
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1 - 1 | boot_media | Boot Media Type (i.e. media emulated by boot image):
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| | Bit 0 to 3 govern emulation
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| | 0= no emulation , 1= 1.2 MB diskette, 2=1.44 MB,
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| | 3= 2.88 MB , 4= hard disk
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| | (About everybody uses 0 = no emulation)
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| | Bit 4 is reserved and must be 0
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| | Bit 5 "Continuation entry follows" (meaning unclear)
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| | Might be the indicator for Extension Entries,
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| | which are not described here.
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| | Bit 6 "Image contains an ATAPI driver"
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| | Bit 7 "Image contains SCSI drivers"
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2 - 3 | load_seg | Load Segment. (meaning unclear)
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| | See above Initial/Default Entry
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| | libisofs default is 0.
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4 - 4 | sys_type | System Type.
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| | See above Initial/Default Entry
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| | 0 if not emulation == 4.
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5 - 5 | 0 | Unused
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6 - 7 | sec_count | Sector Count.
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| | See above Initial/Default Entry
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2010-12-14 05:36:12 +00:00
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| | libisofs stores 1 for emulated boot_media and a
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| | user defined value for boot_media == 0. Often: 4.
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2010-10-14 15:26:56 +00:00
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8 - 11 | load_rba | Load RBA. The 2 kB block address where the boot
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| | image file content is located in the ISO 9660 image.
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12 - 31 | sel_crit | "Vendor unique selection criteria."
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---------- | ---------- | ----------------------------------------------------
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2010-10-12 18:24:17 +00:00
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2010-10-14 15:26:56 +00:00
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The boot image file content is mostly opaque to the ISO 9660 image generator.
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Nevertheless there is a tradition named "Boot Info Table" which prescribes
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to write information into byte fields of the boot image file content.
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There are no general means known how a producer of ISO 9660 images could
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detect the need for Boot Info Table production.
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It rather needs a hint from the user who has to know whether the boot image
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expects a Boot Info Table.
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The Boot Info Table begins at byte 8 of the boot image content.
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2010-10-12 18:24:17 +00:00
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2010-10-14 15:26:56 +00:00
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Byte Range | Value | Meaning
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---------- | ---------- | ----------------------------------------------------
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8 - 11 | pvd_lba | Block address of the Primary Volume Descriptor
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| | This is the session start LBA + 16.
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12 - 15 | file_lba | Block address of the start of the boot image file
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| | content.
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16 - 19 | file_len | Number of bytes in boot image file content.
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20 - 23 | checksum | Little-endian: The sum of all 32-bit words of the
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| | file content from byte 64 to file end.
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24 - 63 | 0 | Reserved
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---------- | ---------- | ----------------------------------------------------
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2010-10-12 18:24:17 +00:00
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------------------------------------------------------------------------------
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2010-10-14 20:34:32 +00:00
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2010-10-14 15:26:56 +00:00
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MBR
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for PC-BIOS x86 from (pseudo-) hard disk
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Sources:
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http://en.wikipedia.org/wiki/Master_boot_record
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2010-10-16 09:24:52 +00:00
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Mailing list conversations with H. Peter Anvin and Vladimir Serbinenko.
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2010-10-14 15:26:56 +00:00
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2010-10-12 18:24:17 +00:00
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2010-10-14 15:26:56 +00:00
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The candidates for MBR booting will normally use El Torito rather than MBR
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if the ISO image is presented on CD, DVD, or BD media.
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2010-11-25 13:40:44 +00:00
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The eventual MBR comes into effect if the image is on a media that is
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2010-10-14 15:26:56 +00:00
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interpreted by the BIOS as some kind of hard disk. Usually real hard disks,
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floppy disks, USB sticks, memory cards.
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2010-10-12 18:24:17 +00:00
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2010-10-16 09:24:52 +00:00
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An important part of an MBR is the DOS style partition table. It describes up
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to four primary partitions. There are two formats used for block address:
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Cylinder/Head/Sector (C/H/S) and Logical Block Address (LBA). Both are based
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on units of 512 bytes. So MBR_LBA = ISO_LBA * 4.
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2010-10-12 18:24:17 +00:00
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2010-10-16 09:24:52 +00:00
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For C/H/S, the sector address is broken up into whole cylinders, remaining
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heads, and remaining sectors + 1. The nomenclature seems to stem from antique
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2010-10-16 09:24:52 +00:00
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drum storage.
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There are two parameters, sectors_per_head and heads_per_cylinder which are not
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stored in the MBR. So it is more or less arbitray how to convert a LBA into
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a C/H/S address and vice versa. For maximum range of C/H/S addresses one
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may use sectors_per_head = 63 , heads_per_cylinder = 255.
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Words are composed little-endian style.
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Byte Range | Value | Meaning
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---------- | ---------- | ----------------------------------------------------
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0 - 439 | = opaque = | Code Area filled with bytes for some boot system,
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| | typically machine code.
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440 - 443 | disk_sgntr | Disc signature, an individual disk id of obscure
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| | usability.
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| | (The Code Area might extend up to this field.)
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444 - 445 | 0 | "usually nulls"
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| | (The Code Area might extend up to this field.)
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446 - 461 | ========== | Partition Table Entry for partition 1
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446 - 446 | status | Governs bootability:
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| | 0x80 = bootable/active , 0x00 non-bootable/inactive
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|
|
|
447 - 449 | ========== | C/H/S address of partition start
|
|
|
|
|
447 - 447 | start_head | Heads part of start address.
|
|
|
|
|
448 - 448 | start_c_s | Bits 0 to 5 : Sectors part of start address.
|
|
|
|
|
| | Bits 6 to 7 : Bits 8 to 9 of cylinders part.
|
|
|
|
|
449 - 449 | start_cyl | Lower 8 bits of cylinders part of start address
|
|
|
|
|
| |
|
|
|
|
|
450 - 450 | part_type | Partition type indicates the purpose or kind of
|
|
|
|
|
| | filesystem in the partition.
|
|
|
|
|
| |
|
|
|
|
|
451 - 453 | ========== | C/H/S address of last absolute sector in partition
|
|
|
|
|
451 - 451 | end_head | Heads part of end address.
|
|
|
|
|
452 - 452 | end_c_s | Bits 0 to 5 : Sectors part of end address.
|
2010-10-18 14:56:00 +00:00
|
|
|
| Values: 1 to 63, not 0.
|
2010-10-16 09:24:52 +00:00
|
|
|
| | Bits 6 to 7 : Bits 8 to 9 of cylinders part.
|
|
|
|
|
453 - 453 | end_cyl | Lower 8 bits of cylinders part of end address
|
|
|
|
|
| |
|
|
|
|
|
454 - 457 | start_lba | LBA of first absolute sector in partiton.
|
|
|
|
|
| | Block size is 512. Counting starts at 0.
|
|
|
|
|
| |
|
|
|
|
|
458 - 461 | num_blocks | Number of sectors in partition.
|
|
|
|
|
| |
|
|
|
|
|
462 - 477 | ========== | Partition Table Entry for partition 2
|
|
|
|
|
| part_entr2 | 16 bytes. Format as with partition 1.
|
|
|
|
|
| | All 0 means that partition is unused/undefined.
|
|
|
|
|
| |
|
|
|
|
|
478 - 493 | ========== | Partition Table Entry for partition 3
|
|
|
|
|
| part_entr3 | 16 bytes. See above.
|
|
|
|
|
| |
|
|
|
|
|
494 - 509 | ========== | Partition Table Entry for partition 4
|
|
|
|
|
| part_entr4 | 16 bytes. See above.
|
|
|
|
|
| |
|
|
|
|
|
510 - 510 | 0x55 | MBR signature
|
|
|
|
|
511 - 511 | 0xaa | MBR signature
|
|
|
|
|
| |
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
By tradition the MBR itself and possibly more blocks are not claimed by any
|
|
|
|
|
partition. But starting the first partition at a non-zero block address causes
|
|
|
|
|
on Linux a partition device file (e.g. /dev/sdb1) which cannot be used to mount
|
|
|
|
|
the ISO filesystem.
|
|
|
|
|
|
|
|
|
|
libisofs is able to produce a second set of trees and meta data which is
|
|
|
|
|
suitable for being mounted at start block 16 (ISO) resp. 64 (MBR).
|
|
|
|
|
See <libisofs/libisofs.h> for call iso_write_opts_set_part_offset()
|
|
|
|
|
and http://libburnia-project.org/wiki/PartitionOffset for examples with
|
|
|
|
|
program xorriso.
|
2010-10-12 18:24:17 +00:00
|
|
|
|
|
|
|
|
|
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
2010-10-14 15:26:56 +00:00
|
|
|
|
2010-10-12 18:24:17 +00:00
|
|
|
SYSLINUX Isohybrid MBR
|
|
|
|
|
|
|
|
|
|
Sources:
|
|
|
|
|
syslinux-3.72/utils/isohybrid , a perl script by H. Peter Anvin = hpa.
|
|
|
|
|
Mailing list conversations with hpa.
|
|
|
|
|
|
2010-10-14 15:26:56 +00:00
|
|
|
|
2010-10-16 09:24:52 +00:00
|
|
|
An isohybrid MBR directs the booting BIOS to an ISOLINUX boot image which
|
2010-10-12 18:24:17 +00:00
|
|
|
is also the target of an El Torito boot catalog entry.
|
|
|
|
|
For that purpose one has to take an MBR template and has to set a few bytes
|
|
|
|
|
to values which sufficiently describe the ISO image and the boot image file.
|
|
|
|
|
|
|
|
|
|
Words are composed little-endian style.
|
|
|
|
|
|
|
|
|
|
Byte Range | Value | Meaning
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
0 - 431 | = opaque = | Syslinux machine code provided by MBR template
|
2010-10-16 09:24:52 +00:00
|
|
|
| |
|
2010-10-12 18:24:17 +00:00
|
|
|
432 - 439 | hd_bootlba | Address of the ISOLINUX boot image file in the
|
|
|
|
|
| | ISO image. Counted in 512 byte blocks.
|
2010-10-16 09:24:52 +00:00
|
|
|
| |
|
2010-10-12 18:24:17 +00:00
|
|
|
440 - 443 | mbr_id | Random number
|
|
|
|
|
444 - 445 | 0 | Padding
|
|
|
|
|
| |
|
|
|
|
|
446 - 509 | ========== | Partition table
|
|
|
|
|
| |
|
|
|
|
|
446 - 461 | part_entry | Partition table entry 1 describing ISO image size
|
2012-05-08 17:46:03 +00:00
|
|
|
| | rounded up to the next full MiB. The partition starts
|
|
|
|
|
| | at LBA 0. (I.e. contrary to tradition.)
|
2010-10-16 09:24:52 +00:00
|
|
|
| | See above for partition table entry format.
|
2010-10-12 18:24:17 +00:00
|
|
|
| |
|
|
|
|
|
462 - 509 | 0 | Unused partition entries 2 to 4
|
|
|
|
|
510 - 511 | 0xaa55 | MBR signature
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
|
2012-05-08 17:46:03 +00:00
|
|
|
The ISO image file gets padded up to the next full MiB.
|
2010-10-12 18:24:17 +00:00
|
|
|
|
|
|
|
|
hpa about MBR templates and partition table filesystem types:
|
|
|
|
|
|
2010-10-14 15:26:56 +00:00
|
|
|
"[MBR templates] are available in the Syslinux build tree under the names:
|
|
|
|
|
mbr/isohdp[fp]x*.bin
|
|
|
|
|
The default probably should be mbr/isohdppx.bin, but it's ultimately up
|
|
|
|
|
to the user.
|
|
|
|
|
[...]
|
|
|
|
|
Note: the filesystem type is largely arbitrary, in theory it can be any
|
|
|
|
|
value other than 0x00, 0x05, 0x0f, 0x85, 0xee, or 0xef. 0x17 ("Windows
|
|
|
|
|
IFS Hidden") seems safeish, some people believe 0x83 (Linux) is better.
|
|
|
|
|
"
|
2010-10-12 18:24:17 +00:00
|
|
|
|
2012-05-06 08:08:21 +00:00
|
|
|
|
|
|
|
|
>>> SYSLINUX isohybrid for UEFI and x86-Mac
|
|
|
|
|
|
|
|
|
|
Sources:
|
|
|
|
|
http://mjg59.dreamwidth.org/11285.html
|
|
|
|
|
http://mjg59.fedorapeople.org/Fedora-LiveCD.iso
|
|
|
|
|
http://opensource.apple.com/source/IOStorageFamily/IOStorageFamily-116/IOApplePartitionScheme.h (typedef struct Block0)
|
|
|
|
|
http://www.informit.com/articles/article.aspx?p=376123&seqNum=3
|
|
|
|
|
http://en.wikipedia.org/wiki/GUID_Partition_Table
|
2012-05-08 17:46:03 +00:00
|
|
|
http://en.wikipedia.org/wiki/GUID
|
2012-05-06 08:08:21 +00:00
|
|
|
syslinux-4.05/utils/isohybrid.c
|
|
|
|
|
|
|
|
|
|
>>> Motivation: What systems will use the additional data ? amd64 UEFI ?
|
|
|
|
|
|
2012-05-09 10:03:50 +00:00
|
|
|
This is a very condensed format which exposes a lot of entry points for boot
|
|
|
|
|
firmware.
|
2012-05-06 12:11:34 +00:00
|
|
|
|
2012-05-09 10:03:50 +00:00
|
|
|
Byte Range | Value | Meaning
|
2012-05-06 12:11:34 +00:00
|
|
|
-------------- | ---------- | -------------------------------------------------
|
|
|
|
|
0 - 511 | mbr | Isohybrid MBR pointing to x86 boot image file,
|
|
|
|
|
| | with three entries in its partition map.
|
|
|
|
|
| | It shares its first 32 bytes with apm_head.
|
|
|
|
|
0 - 31 | apm_head | Mock-up of the start of the first block of
|
|
|
|
|
| | an Apple Partition Map (APM).
|
2012-05-09 10:03:50 +00:00
|
|
|
446 - 461 | mbr_entry1 | Partition table entry 1 describing the size of
|
|
|
|
|
| | the ISO image plus the backup GPT, padded up to
|
|
|
|
|
| | the next full MiB.
|
2012-05-06 12:11:34 +00:00
|
|
|
462 - 477 | mbr_entry2 | Entry 2 describing the UEFI VFAT boot image.
|
|
|
|
|
478 - 493 | mbr_entry3 | Entry 3 describing the HFS+ boot image.
|
|
|
|
|
| |
|
|
|
|
|
512 - 1023 | gpt_head | GPT header describing the GPT partition array.
|
|
|
|
|
1024 - 2047 | unused |
|
|
|
|
|
2048 - 4095 | apm_entry1 | APM entry 1 describing ISO image size.
|
|
|
|
|
4096 - 6143 | apm_entry2 | APM entry 2 describing the UEFI VFAT boot image.
|
2012-05-07 18:33:53 +00:00
|
|
|
6144 - 8195 | apm_entry3 | APM entry 3 describing the HFS+ boot image.
|
2012-05-06 12:11:34 +00:00
|
|
|
8192 - 8319 | gpt_entry1 | GPT partition entry 1 for the ISO image size.
|
|
|
|
|
8320 - 8447 | gpt_entry2 | GPT partition entry 2 for UEFI VFAT boot image,
|
|
|
|
|
8448 - 8575 | gpt_entry3 | GPT partition entry 3 for the HFS+ boot image.
|
|
|
|
|
8576 - 24575 | gtp_empty | Empty GPT partition entries 4 to 128.
|
|
|
|
|
24576 - 32767 | unused |
|
|
|
|
|
32768 - 34815 | iso_pvd | ISO 9660 superblock
|
2012-05-07 18:33:53 +00:00
|
|
|
34816 - 36863 | el_torito | EL Torito boot block pointing to a boot catalog
|
|
|
|
|
| | with entries for the MBR boot image (platform id
|
2012-05-06 12:11:34 +00:00
|
|
|
| | 0x00), and for the two other boot images
|
|
|
|
|
| | (platform id 0xef)
|
|
|
|
|
-------------- | ---------- | -------------------------------------------------
|
|
|
|
|
|
|
|
|
|
|
2012-05-09 10:03:50 +00:00
|
|
|
For the purpose of booting, there may be two EFI boot image files in the
|
|
|
|
|
ISO image. A VFAT image and a HFS+ image. The content of both is not in the
|
|
|
|
|
scope of this document.
|
|
|
|
|
These boot images get announced by EL Torito boot catalog entries with
|
|
|
|
|
Platform Id 0xef.
|
|
|
|
|
|
|
|
|
|
|
2012-05-06 08:08:21 +00:00
|
|
|
Newer SYSLINUX MBR templates begin by 32 bytes of machine code which are
|
|
|
|
|
intentionally non-essential:
|
|
|
|
|
33 ed 90 90 90 90 90 90 90 90 90 90 90 90 90 90
|
|
|
|
|
90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
|
|
|
|
|
They may be overwritten by other bytes which must not produce errors or
|
|
|
|
|
undesirable side effects when executed as x86 machine code.
|
|
|
|
|
The following 32 bytes from block 0 of an Apple Partiton Map (APM) are such
|
|
|
|
|
harmless code. They stem from Fedora-LiveCD.iso by Matthew Garret:
|
|
|
|
|
45 52 08 00 00 00 90 90 00 00 00 00 00 00 00 00
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
2012-05-09 10:03:50 +00:00
|
|
|
They do not depend on any properties of the ISO image or the information
|
|
|
|
|
that is described in the following text.
|
2012-05-06 08:08:21 +00:00
|
|
|
|
|
|
|
|
The layout of a Block0 of an APM is:
|
|
|
|
|
|
|
|
|
|
Byte Range | Value | Meaning (all numbers are stored big endian)
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
0 - 1 | sig | Signature 0x45 = 'E' , 0x52 = 'R'
|
|
|
|
|
2 - 3 | block_size | 0x0800 = 2048
|
|
|
|
|
4 - 7 | block_count| 0x9090 = 37008
|
|
|
|
|
8 - 9 | dev_type | obscure: "device type"
|
|
|
|
|
10 - 11 | dev_id | obscure: "device id"
|
|
|
|
|
12 - 15 | drv_data | obscure: "driver data"
|
|
|
|
|
16 - 17 | drv_count | obscure: "driver descriptor count"
|
|
|
|
|
18 - 81 | drv_map | obscure: "driver descriptor table"
|
|
|
|
|
| | with 8 entries of 16 bytes each
|
|
|
|
|
82 - 511 | reserved |
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
|
|
|
|
|
(The block_count of 0x9090 is pure fantasy. It shall only mark the disc as
|
|
|
|
|
not empty.)
|
|
|
|
|
|
|
|
|
|
The data block ranges of the two EFI boot images get described by MBR
|
|
|
|
|
partition entries 2 and 3, which thus claim blocks inside of partition 1.
|
|
|
|
|
This partition nesting is acceptable to some EFI implementations only if the
|
|
|
|
|
type of partition 1 is 0x00.
|
|
|
|
|
|
2012-05-08 17:46:03 +00:00
|
|
|
The MBR partition entry number 1 is
|
|
|
|
|
80 00 01 00 00 3f a0 89 00 00 00 00 00 50 14 00
|
|
|
|
|
It marks the partition as bootable, starting at block 0, with a size that
|
|
|
|
|
is the smallest full MiB not smaller than the ISO image size + 18 KiB.
|
|
|
|
|
(The 18 KiB are needed for the GPT backup.)
|
|
|
|
|
The ISO image has a size of 332362 blocks of 2K = 1329448 * 512 = 649.14 MiB.
|
|
|
|
|
The partition size is 0x145000 = 1331200 * 512 = 650 MiB.
|
|
|
|
|
Start C/H/S = 0/0/1, type is 0x0 ("Empty"), end C/H/S is 649/63/32.
|
|
|
|
|
|
|
|
|
|
Partition 2:
|
|
|
|
|
00 fe ff ff ef fe ff ff a4 00 00 00 70 04 00 00
|
|
|
|
|
Start block is 0xa4 = 164 * 512 = 41 * 2048. The VFAT image file.
|
|
|
|
|
Partition size is 0x0470 = 1136 * 512. The size of that file.
|
|
|
|
|
Start C/H/S = 1023/254/63, type 0xef (fdisk says: "EFI (FAT-12/16/"),
|
|
|
|
|
end C/H/S = 1023/254/63.
|
|
|
|
|
>>> ??? why are the C/H/S values so far out ?
|
|
|
|
|
|
|
|
|
|
Partition 3:
|
|
|
|
|
00 fe ff ff 00 fe ff ff 44 05 00 00 c0 08 00 00
|
|
|
|
|
Start block is 0x0544 = 1348 * 512 = 337 * 2048. The HFS+ image file.
|
|
|
|
|
Partition size is 0x08c0 = 2240 * 512. The size of that file.
|
|
|
|
|
Start C/H/S = 1023/254/63, type 0x00 ("Empty"), end C/H/S = 1023/254/63.
|
|
|
|
|
>>> ??? why are the C/H/S values so far out ?
|
|
|
|
|
|
2012-05-06 08:08:21 +00:00
|
|
|
|
|
|
|
|
The second 512-block in the ISO image is a GPT header.
|
|
|
|
|
|
|
|
|
|
45 46 49 20 50 41 52 54 00 00 01 00 5c 00 00 00
|
|
|
|
|
E F I P A R T
|
|
|
|
|
13 db 71 5d 00 00 00 00 01 00 00 00 00 00 00 00
|
|
|
|
|
fe 4f 14 00 00 00 00 00 30 00 00 00 00 00 00 00
|
|
|
|
|
de 4f 14 00 00 00 00 00 73 23 c8 79 19 e6 97 4d
|
|
|
|
|
95 17 69 30 c5 38 e2 99 10 00 00 00 00 00 00 00
|
|
|
|
|
80 00 00 00 80 00 00 00 5b 6b 8a 65
|
|
|
|
|
|
|
|
|
|
Byte Range | Value | Meaning (little endian numbers, LBA unit is 512 byte)
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
0 - 7 | sig | Signature "EFI PART" (with no trailing zero)
|
|
|
|
|
8 - 11 | revision | Revision = {0x00, 0x00, 0x01, 0x00} meaning "1.0"
|
|
|
|
|
12 - 15 | head_size | Header size = 0x5c = 92
|
|
|
|
|
16 - 19 | head_crc | CRC-32 of this header while head_crc is 0
|
|
|
|
|
20 - 23 | reserved | = 0
|
|
|
|
|
24 - 31 | curr_lba | Location of this header block = 0x1
|
|
|
|
|
32 - 39 | back_lba | Location of header backup block = 0x144ffe = 1331198
|
2012-05-09 10:03:50 +00:00
|
|
|
| | This is 1 KiB before the end of MBR partition 1
|
|
|
|
|
| | (but should be 512 bytes).
|
|
|
|
|
| | (Potential isohybrid.c bug #1:
|
|
|
|
|
| | Backup GPT is dislocated by 512 bytes.)
|
2012-05-06 08:08:21 +00:00
|
|
|
40 - 47 | first_lba | First usable LBA for partitions = 0x30 = 48
|
|
|
|
|
48 - 55 | last_lba | Last usable LBA for partitions = 0x144fde = 1331166
|
2012-05-08 17:46:03 +00:00
|
|
|
56 - 71 | guid | Disk GUID
|
|
|
|
|
| | Random, produced by uuid_generate(),
|
|
|
|
|
| | 32,16,16 byte swapped
|
2012-05-06 08:08:21 +00:00
|
|
|
72 - 79 | part_start | Partition entries start LBA = 0x10 = 16 = byte 0x2000
|
|
|
|
|
| | (This is unusual. It leaves room for the Apple
|
|
|
|
|
| | partition map entries.)
|
|
|
|
|
80 - 83 | entry_count| Number of partition entries = 0x80 = 128
|
|
|
|
|
84 - 87 | entry_size | Size of a partition entry = 0x80 = 128
|
|
|
|
|
88 - 91 | p_arr_crc | CRC-32 of the partition array
|
|
|
|
|
92 - 511 | reserved | Must be 0
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
|
2012-05-07 18:33:53 +00:00
|
|
|
The CRC-32 algorithm can be characterized as follows:
|
|
|
|
|
The generating polynomial has the bit representation 0x104c11db7.
|
|
|
|
|
The seed value for a bit shifting division algorithm is 0x46af6449. It is
|
2012-05-07 18:50:48 +00:00
|
|
|
chosen so that the CRC of 0 bytes of input is 0x00000000.
|
2012-05-07 18:33:53 +00:00
|
|
|
The least significant bits of input bytes get processed first. I.e. bit0 of
|
|
|
|
|
the last input byte gets mapped to x exp (7 + 32), bit7 of this byte gets
|
|
|
|
|
mapped to x exp (0 + 32).
|
2012-05-08 17:46:03 +00:00
|
|
|
The resulting division residue gets bitwise mirrored. E.g. bit0 becomes bit31,
|
2012-05-07 18:33:53 +00:00
|
|
|
bit1 becomes bit30, and so on. Further it gets exored with 0xffffffff.
|
|
|
|
|
|
2012-05-08 17:46:03 +00:00
|
|
|
A GUID consists of a 32-bit integer, two 16-bit integers, and an array of
|
|
|
|
|
8 bytes. The integers are to be stored big-endian.
|
|
|
|
|
A globally registered class GUID are the partition type GUIDs.
|
|
|
|
|
This example uses two of them
|
|
|
|
|
Basic data partition: a2 a0 d0 eb , e5 b9 , 33 44 , 87 c0 68 b6 b7 26 99 c7
|
|
|
|
|
HFS+ partition : 00 53 46 48 , 00 00 , aa 11 , aa 11 00 30 65 43 ec ac
|
|
|
|
|
Note that the wikipedia list shows the first 32-bit word and the next two
|
|
|
|
|
16-bit words in little-endia interpretation.
|
2012-05-06 08:08:21 +00:00
|
|
|
|
|
|
|
|
|
|
|
|
|
Because the block size was announced as 2048, the first Apple partition map
|
2012-05-07 18:33:53 +00:00
|
|
|
entry is located at byte 0x800 = 2048.
|
2012-05-06 08:08:21 +00:00
|
|
|
It describes the partition map itself:
|
|
|
|
|
50 4d 00 00 00 00 00 03 00 00 00 01 00 00 00 10
|
|
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|
|
P M
|
|
|
|
|
41 70 70 6c 65 00 00 00 00 00 00 00 00 00 00 00
|
|
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|
|
A p p l e
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
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|
|
41 70 70 6c 65 5f 70 61 72 74 69 74 69 6f 6e 5f
|
|
|
|
|
A p p l e _ p a r t i t i o n _
|
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|
|
|
6d 61 70 00 00 00 00 00 00 00 00 00 00 00 00 00
|
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|
|
m a p
|
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|
|
|
00 00 00 00 00 00 00 0a 00 00 00 03 00 00 00 00
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|
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|
|
|
The layout of an Apple partition map entry is:
|
|
|
|
|
|
|
|
|
|
Byte Range | Value | Meaning (all numbers are stored big endian)
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
0 - 1 | sig | Signature 0x50 = 'P' , 0x4d = 'M'
|
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|
|
2 - 3 | reserved |
|
|
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|
|
4 - 7 | map_entries| "number of partition entries" = 3
|
|
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|
|
8 - 11 | start_block| "physical block start of partition" = 1
|
|
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|
|
12 - 15 | block_count| "physical block count of partition" = 16
|
|
|
|
|
| | (The value of 16 claims the ISO 9660 PVD as part of
|
2012-05-09 10:03:50 +00:00
|
|
|
| | the partition table. It should be 4 instead.)
|
2012-05-06 08:08:21 +00:00
|
|
|
16 - 47 | name | Partition name = "Apple"
|
|
|
|
|
48 - 79 | type | Type string = "Apple_partition_map"
|
|
|
|
|
80 - 83 | lb_start | Logical block start = 0
|
|
|
|
|
84 - 87 | lb_count | Logical block count = 10
|
|
|
|
|
88 - 91 | flags | Status flags = 3
|
|
|
|
|
| | bit0= entry is valid
|
|
|
|
|
| | bit1= entry is allocated
|
|
|
|
|
| | bit4= partition is readable
|
|
|
|
|
| | bit5= partition is writable
|
|
|
|
|
92 - 95 | boot_block | Logical start block number of boot code = 0
|
|
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|
|
96 - 99 | boot_bytes | Number of bytes in boot code = 0
|
|
|
|
|
100 - 119 | | More boot code stuff = 0
|
|
|
|
|
120 - 135 | processor | "processor type" = 0
|
|
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|
|
136 - 511 | reserved |
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
|
2012-05-09 10:03:50 +00:00
|
|
|
(Potential isohybrid.c bug #2:
|
|
|
|
|
Apple partition map entries bear the block count for blocks of 512 bytes
|
|
|
|
|
whereas Apple Block0 announces blocks of 2048 bytes.)
|
|
|
|
|
|
2012-05-07 18:33:53 +00:00
|
|
|
The next Apple partition map entry is at byte 0x1000 = 4096:
|
2012-05-06 08:08:21 +00:00
|
|
|
|
|
|
|
|
50 4d 00 00 00 00 00 03 00 00 00 29 00 00 04 70
|
|
|
|
|
45 46 49 00 00 00 00 00 00 00 00 00 00 00 00 00
|
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|
|
E F I
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
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|
|
41 70 70 6c 65 5f 48 46 53 00 00 00 00 00 00 00
|
|
|
|
|
A p p l e _ H F S
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
00 00 00 00 00 00 04 70 00 00 00 33 00 00 00 00
|
|
|
|
|
|
2012-05-09 10:03:50 +00:00
|
|
|
3 partitions, start block is 0x29 = 41,
|
|
|
|
|
block count is 0x0470 = 1136 (should be 284), name is "EFI",
|
|
|
|
|
type is "Apple_HFS" (although this is a FAT image),
|
|
|
|
|
logical block start = 0, lb_count = 1136 (should be 284),
|
2012-05-06 08:08:21 +00:00
|
|
|
flags = 0x33 : valid, allocated, readable, writable.
|
2012-05-09 10:03:50 +00:00
|
|
|
This points to file /isolinux/efiboot.img in the ISO image.
|
|
|
|
|
(Potential isohybrid.c bug #2:
|
|
|
|
|
Apple partition map entries bear the block count for blocks of 512 bytes
|
|
|
|
|
whereas Apple Block0 announces blocks of 2048 bytes.)
|
2012-05-06 08:08:21 +00:00
|
|
|
|
2012-05-09 10:03:50 +00:00
|
|
|
At byte 0x1800 = 6144, there is Apple partition map entry 3:
|
2012-05-06 08:08:21 +00:00
|
|
|
|
|
|
|
|
50 4d 00 00 00 00 00 03 00 00 01 51 00 00 08 c0
|
|
|
|
|
45 46 49 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
E F I
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
41 70 70 6c 65 5f 48 46 53 00 00 00 00 00 00 00
|
|
|
|
|
A p p l e _ H F S
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
00 00 00 00 00 00 08 c0 00 00 00 33 00 00 00 00
|
|
|
|
|
|
|
|
|
|
3 partitions, start block is 0x0151 = 337 (LBA of /isolinux/macboot.img),
|
2012-05-09 10:03:50 +00:00
|
|
|
block count = 0x08c0 = 2240 (should be 560), name is "EFI",
|
|
|
|
|
type is "Apple_HFS", logical block start = 0, lb_count = 2240 (should be 560),
|
2012-05-06 08:08:21 +00:00
|
|
|
flags = 0x33 : valid, allocated, readable, writable.
|
2012-05-09 10:03:50 +00:00
|
|
|
(Potential isohybrid.c bug #2:
|
|
|
|
|
Apple partition map entries bear the block count for blocks of 512 bytes
|
|
|
|
|
whereas Apple Block0 announces blocks of 2048 bytes.)
|
2012-05-06 08:08:21 +00:00
|
|
|
|
2012-05-07 18:33:53 +00:00
|
|
|
At byte 0x2000 = 8192 begins the GPT partition array.
|
|
|
|
|
It ends at byte 0x4000 = 16384.
|
2012-05-06 08:08:21 +00:00
|
|
|
|
|
|
|
|
a2 a0 d0 eb e5 b9 33 44 87 c0 68 b6 b7 26 99 c7
|
|
|
|
|
a1 87 a1 ba 4d 2c 27 45 ae 05 cf ab a6 fa 87 c1
|
|
|
|
|
00 00 00 00 00 00 00 00 28 49 14 00 00 00 00 00
|
|
|
|
|
00 00 00 00 00 00 00 00 49 53 4f 48 79 62 72 69
|
|
|
|
|
I S O H y b r i
|
|
|
|
|
64 20 49 53 4f 00 49 53 4f 48 79 62 72 69 64 00
|
|
|
|
|
d I S O I S O H y b r i d
|
|
|
|
|
41 70 70 6c 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
A p p l
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
|
|
|
|
|
A GPT partion entry looks like:
|
|
|
|
|
|
|
|
|
|
Byte Range | Value | Meaning (numbers are stored little endian)
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
2012-05-09 10:03:50 +00:00
|
|
|
0 - 15 | type_guid | Partition type GUID = Basic data partition
|
2012-05-08 17:46:03 +00:00
|
|
|
| | Wikipedia: "EBD0A0A2-B9E5-4433-87C0-68B6B72699C7"
|
|
|
|
|
| | (Note: The first three words are shown byte swapped)
|
|
|
|
|
16 - 31 | part_guid | Unique partition GUID
|
|
|
|
|
| | Random, produced by uuid_generate()
|
|
|
|
|
| | 32,16,16 byte swapped
|
2012-05-06 08:08:21 +00:00
|
|
|
32 - 39 | start_lba | First LBA = 0
|
|
|
|
|
40 - 47 | end_lba | Last LBA (inclusive) = 0x144828 = 1329448
|
|
|
|
|
| | This is the ISO image size in blocks of 512.
|
2012-05-09 10:03:50 +00:00
|
|
|
| | (Potential isohybrid.c bug #3:
|
|
|
|
|
| | The end_lba in the first GPT entry should be 1 less
|
|
|
|
|
| | than the count of 512 byte blocks of the ISO image.)
|
2012-05-06 08:08:21 +00:00
|
|
|
48 - 55 | flags | Attribute flags
|
|
|
|
|
| | bit0= "System Partition" Do not alter.
|
|
|
|
|
| | bit2= Legacy BIOS bootable (MBR partition type 0x80)
|
|
|
|
|
| | bit60= read-only
|
2012-05-09 10:03:50 +00:00
|
|
|
56 - 127 | name | Wikipedia says UTF-16LE.
|
|
|
|
|
| | (Potential isohybrid.c bug #4:
|
|
|
|
|
| | The name in Fedora-LiveCD.iso is 8 bit and result
|
|
|
|
|
| | of faulty memory operation on a text constant.)
|
2012-05-06 08:08:21 +00:00
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
|
2012-05-07 18:33:53 +00:00
|
|
|
Next entry is at 0x2800 = 10240:
|
2012-05-06 08:08:21 +00:00
|
|
|
|
|
|
|
|
a2 a0 d0 eb e5 b9 33 44 87 c0 68 b6 b7 26 99 c7
|
|
|
|
|
c8 de c8 1f fb f0 51 40 8c 8a d2 f6 b1 46 16 dc
|
|
|
|
|
a4 00 00 00 00 00 00 00 13 05 00 00 00 00 00 00
|
|
|
|
|
00 00 00 00 00 00 00 00 49 53 4f 48 79 62 72 69
|
|
|
|
|
I S O H y b r i
|
|
|
|
|
64 00 41 70 70 6c 65 00 41 70 70 6c 00 00 00 00
|
|
|
|
|
d A p p l e A p p l
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
|
2012-05-08 17:46:03 +00:00
|
|
|
Partition type GUID : "EBD0A0A2-B9E5-4433-87C0-68B6B72699C7" = Basic data
|
2012-05-06 08:08:21 +00:00
|
|
|
Start at block 0xa4 = 164 * 512 = 41 * 2048. The VFAT image file.
|
|
|
|
|
Last block is 0x0513 = 1299 = 164 + 1135. This end is correct.
|
2012-05-09 10:03:50 +00:00
|
|
|
(Potential isohybrid.c bug #4:
|
|
|
|
|
Wrong character set and incidential bytes in GPT partition name.)
|
2012-05-06 08:08:21 +00:00
|
|
|
|
2012-05-07 18:33:53 +00:00
|
|
|
Next entry at byte 0x02100 = 8448:
|
2012-05-06 08:08:21 +00:00
|
|
|
|
|
|
|
|
00 53 46 48 00 00 aa 11 aa 11 00 30 65 43 ec ac
|
|
|
|
|
c8 de c8 1f fb f0 51 40 8c 8a d2 f6 b1 46 16 dc
|
|
|
|
|
44 05 00 00 00 00 00 00 03 0e 00 00 00 00 00 00
|
|
|
|
|
00 00 00 00 00 00 00 00 49 53 4f 48 79 62 72 69
|
|
|
|
|
I S O H y b r i
|
|
|
|
|
64 00 41 70 70 6c 65 00 41 70 70 6c 00 00 00 00
|
|
|
|
|
d A p p l e A p p l
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|
|
|
|
|
|
2012-05-08 17:46:03 +00:00
|
|
|
Partition type GUID : "48465300-0000-11AA-AA11-00306543ECAC" = HFS+
|
2012-05-06 08:08:21 +00:00
|
|
|
Start block is 0x0544 = 1348 * 512 = 337 * 2048. The HFS+ image file.
|
|
|
|
|
Last block is 0x0e03 = 3587 = 1348 + 2239. Correct.
|
2012-05-09 10:03:50 +00:00
|
|
|
(Potential isohybrid.c bug #4:
|
|
|
|
|
Wrong character set and incidential bytes in GPT partition name.)
|
2012-05-06 08:08:21 +00:00
|
|
|
|
|
|
|
|
The rest of the System Area is 0 up to the Primary Volume Descriptor
|
|
|
|
|
at block 16.
|
|
|
|
|
|
2012-05-08 17:46:03 +00:00
|
|
|
|
|
|
|
|
The ISO image file gets padded up to full MiB with sufficient room for the GPT
|
|
|
|
|
backup which is stored near the very end of the image file. There is need for
|
|
|
|
|
at least 16.5 KiB, which effectively occupy 18 KiB.
|
|
|
|
|
|
|
|
|
|
The backup partition array is stored 17 KiB before the end of MBR partition 1
|
|
|
|
|
resp. the image file.
|
2012-05-09 10:03:50 +00:00
|
|
|
(Potential isohybrid.c bug #1:
|
|
|
|
|
Wikipedia suggests "LBA -33" counted from end. This would be 16.5 KiB before
|
|
|
|
|
end.)
|
|
|
|
|
|
2012-05-08 17:46:03 +00:00
|
|
|
The content of the partition arry is the same as the one of the primary array
|
|
|
|
|
at byte 0x4000.
|
|
|
|
|
|
|
|
|
|
The GPT header is stored 1 KiB before the end of MBR partition 1.
|
2012-05-09 10:03:50 +00:00
|
|
|
(Potential isohybrid.c bug #1:
|
|
|
|
|
Wikipedia suggests "LBA -1" counted from end. This ould be 512 bytes.)
|
2012-05-08 17:46:03 +00:00
|
|
|
|
|
|
|
|
45 46 49 20 50 41 52 54 00 00 01 00 5c 00 00 00
|
|
|
|
|
E F I P A R T
|
|
|
|
|
f6 61 10 1c 00 00 00 00 fe 4f 14 00 00 00 00 00
|
|
|
|
|
01 00 00 00 00 00 00 00 30 00 00 00 00 00 00 00
|
|
|
|
|
de 4f 14 00 00 00 00 00 73 23 c8 79 19 e6 97 4d
|
|
|
|
|
95 17 69 30 c5 38 e2 99 de 4f 14 00 00 00 00 00
|
|
|
|
|
80 00 00 00 80 00 00 00 5b 6b 8a 65
|
|
|
|
|
|
|
|
|
|
It differs by its own CRC and by some of its parameters:
|
|
|
|
|
Own address is 0x144ffe. The backup lba is 0x01 = Primary GPT header.
|
|
|
|
|
Partition entries start is 0x144fde
|
2012-05-09 10:03:50 +00:00
|
|
|
(Potential isohybrid.c bug #1:
|
|
|
|
|
This overlaps with the last usable LBA. The backup GPT must move up by
|
|
|
|
|
512 bytes.)
|
2012-05-08 17:46:03 +00:00
|
|
|
|
|
|
|
|
|
2010-10-14 15:26:56 +00:00
|
|
|
------------------------------------------------------------------------------
|
2010-10-12 18:24:17 +00:00
|
|
|
|
|
|
|
|
|
2010-10-14 15:26:56 +00:00
|
|
|
GRUB2 grub-mkrescue MBR
|
2010-10-12 18:24:17 +00:00
|
|
|
|
2010-10-14 15:26:56 +00:00
|
|
|
Sources:
|
|
|
|
|
Mailing list conversations with Vladimir Serbinenko.
|
2010-10-12 18:24:17 +00:00
|
|
|
|
|
|
|
|
|
2010-10-14 15:26:56 +00:00
|
|
|
The MBR file that is used with GRUB2 script grub-mkrescue needs only a
|
|
|
|
|
partition table entry which describes the image size.
|
|
|
|
|
|
|
|
|
|
Byte Range | Value | Meaning
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
0 - 445 | = opaque = | GRUB2 machine code provided by MBR template
|
|
|
|
|
| |
|
|
|
|
|
446 - 509 | ========== | Partition table
|
|
|
|
|
| |
|
|
|
|
|
446 - 461 | part_entry | Partition table entry 1 describing ISO image size
|
|
|
|
|
| | Peculiar is the start offset of 1 block.
|
|
|
|
|
| | This prevents mounting of the partition.
|
2010-10-16 09:24:52 +00:00
|
|
|
| | See above for partition table entry format.
|
2010-10-14 15:26:56 +00:00
|
|
|
| |
|
|
|
|
|
462 - 509 | 0 | Unused partition entries 2 to 4
|
|
|
|
|
510 - 511 | 0xaa55 | MBR signature
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
|
|
|
|
|
Vladimir Serbinenko about the partition table entry:
|
|
|
|
|
"Currently we use first and not last entry. You need to:
|
|
|
|
|
1) Zero-fill 446-510
|
|
|
|
|
2) Put 0x55, 0xAA into 510-512
|
|
|
|
|
3) Put 0x80 (for bootable partition), 0, 2, 0 (C/H/S of the start), 0xcd
|
|
|
|
|
(partition type), [3 bytes of C/H/S end], 0x01, 0x00, 0x00, 0x00 (LBA
|
|
|
|
|
start in little endian), [LBA end in little endian] at 446-462
|
|
|
|
|
"
|
2010-10-12 18:24:17 +00:00
|
|
|
|
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
MIPS Volume Header
|
|
|
|
|
for MIPS Big Endian, e.g. SGI Indigo2
|
|
|
|
|
|
|
|
|
|
Sources:
|
|
|
|
|
cdrkit-1.1.10/genisoimage/boot-mips.c
|
|
|
|
|
by Steve McIntyre <steve@einval.com>
|
|
|
|
|
which refers to
|
|
|
|
|
genisovh by Florian Lohoff <flo@rfc822.org>
|
|
|
|
|
and Thiemo Seufer <seufer@csv.ica.uni-stuttgart.de>
|
|
|
|
|
who seem to have learned parameter settings from IRIX CD media
|
|
|
|
|
There are traces in the web which relate this to specs by
|
|
|
|
|
MIPS Computer Systems, Inc. , 1985
|
|
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|
|
Silicon Graphics Computer Systems, Inc. , 2000
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
The first 512 bytes of the media constitute the Volume Header.
|
|
|
|
|
Words are composed big-endian style.
|
|
|
|
|
|
|
|
|
|
Byte Range | Value | Meaning
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
0 - 3 | 0x0be5a941 | Magic number
|
|
|
|
|
4 - 5 | 0 | Root partition number
|
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|
|
6 - 7 | 0 | Swap partition number
|
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|
|
8 - 23 | 0 | Name of file to boot (unclear what this means)
|
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|
|
| |
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|
|
|
24 - 71 | ========== | Device Parameters
|
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|
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| |
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|
24 - 24 | 0 | Spiral addressing skew (unclear what this means)
|
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|
|
25 - 25 | 0 | Words of 0 before header
|
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|
26 - 26 | 0 | Words of 0 between hdr and data
|
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|
27 - 27 | 0 | Spare sectors per cylinder
|
|
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|
28 - 29 | num_cyl_l | Number of usable cylinder, lower two bytes
|
|
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|
|
| | ((iso_size + BYTES_PER_SECTOR - 1) /
|
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|
|
|
| | (SECTORS_PER_TRACK * BYTES_PER_SECTOR)) & 0xffff
|
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|
30 - 31 | 0 | Starting head of volume 0
|
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|
32 - 33 | 1 | Number of tracks per cylinder
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|
34 - 34 | 0 | Depth of CTQ queue (unclear what this means)
|
|
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|
35 - 35 | num_cyl_h | Number of usable cylinders, high byte
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|
|
| | ((iso_size + BYTES_PER_SECTOR - 1) /
|
|
|
|
|
| | (SECTORS_PER_TRACK * BYTES_PER_SECTOR)) >> 16
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36 - 37 | 0 | unused
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38 - 39 | 32 | SECTORS_PER_TRACK
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40 - 41 | 512 | BYTES_PER_SECTOR
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42 - 43 | 0 | Sector interleave (unclear what this means)
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44 - 47 | 0x00000034 | Controller characteristics composed from
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| | DP_RESEEK 0x00000020 /* recalibrate as last resort */
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| | DP_IGNOREERRORS 0x00000010
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| | /* transfer data regardless of errors */
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| | DP_TRKFWD 0x00000004
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| | /* forward to replacement track */
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48 - 51 | 0 | Bytes/sec for kernel stats
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52 - 55 | 0 | Max num retries on data error
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56 - 59 | 0 | ms per word to xfer, for iostat
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60 - 71 | 0 | 6 parameter words for xylogics controllers
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| |
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|
72 - 311 | ========== | Volume Directory with 15 entries of 16 bytes each
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| |
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72 - 87 | ========== | Volume Directory Entry 1
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72 - 79 | boot_name | Boot file basename, eventually padded by 0 to lenght 8
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80 - 83 | boot_block | ISO 9660 LBA of boot file * 4, i.e. in blocks of 512
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|
84 - 87 | boot_bytes | File length in bytes
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| |
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|
88 - 311 | see above | Volume Directory Entries 2 to 15
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| |
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|
312 - 504 | ========== | Partition Table with 16 entries of 12 bytes each
|
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| |
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|
312 - 407 | 0 | Unused partition entries 1 to 8
|
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| |
|
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|
408 - 419 | ========== | Partition Table Entry 9 for Volume Header
|
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|
408 - 411 | part_blks | Number of 512 byte blocks in partition
|
|
|
|
|
| |(iso_size + (BYTES_PER_SECTOR - 1)) / BYTES_PER_SECTOR
|
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|
412 - 415 | 0 | Start block of partition
|
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|
|
416 - 419 | 0 | PTYPE_VOLHDR = Partition is volume header
|
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|
| |
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|
|
420 - 431 | 0 | Unused partition entry 10
|
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|
| |
|
|
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|
|
432 - 443 | ========== | Partition Table Entry 11 for Volume
|
|
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|
|
432 - 435 | part_blks | Number of 512 byte blocks in partition
|
|
|
|
|
| |(iso_size + (BYTES_PER_SECTOR - 1)) / BYTES_PER_SECTOR
|
|
|
|
|
436 - 439 | 0 | Start block of partition
|
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|
|
440 - 443 | 6 | PTYPE_VOLUME = Partition is entire volume
|
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|
| |
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|
|
444 - 503 | 0 | Unused partition entries 12 to 16
|
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|
| |
|
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|
|
504 - 507 | head_chk | Volume header checksum
|
|
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|
|
| | The two's complement of bytes 0 to 503 read as big
|
|
|
|
|
| | endian unsigned 32 bit: sum(words) + head_chk == 0
|
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|
| |
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|
|
508 - 511 | 0 | Volume header end padding
|
|
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|
| |
|
|
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|
|
up to 2048 | 0 | ISO 9660 Block end padding
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
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|
|
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|
|
------------------------------------------------------------------------------
|
|
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|
|
2010-10-14 20:34:32 +00:00
|
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|
|
DEC Boot Block
|
|
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|
|
for MIPS Little Endian , e.g. DECstation
|
2010-10-14 15:26:56 +00:00
|
|
|
|
|
|
|
|
Sources:
|
|
|
|
|
cdrkit-1.1.10/genisoimage/boot-mipsel.c
|
|
|
|
|
by Steve McIntyre <steve@einval.com>
|
|
|
|
|
which refers to
|
|
|
|
|
delo by Florian Lohoff <flo@rfc822.org>
|
|
|
|
|
and Thiemo Seufer <seufer@csv.ica.uni-stuttgart.de>
|
|
|
|
|
cdrkit-1.1.10/include/glibc_elf.h
|
|
|
|
|
by Steve McIntyre
|
|
|
|
|
which is based on
|
|
|
|
|
<elf.h> from GNUC C Library by Free Software Foundation, Inc.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
There seems to be only one boot file possible.
|
2010-10-14 20:34:32 +00:00
|
|
|
Some information needs to be read out of the ELF headers of this boot file.
|
2010-10-14 15:26:56 +00:00
|
|
|
|
|
|
|
|
Byte Range | Value | Meaning
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
0 - 7 | 0 | Padding
|
|
|
|
|
| |
|
|
|
|
|
8 - 11 | 0x0002757a | Magic number
|
|
|
|
|
| |
|
|
|
|
|
12 - 15 | 1 | Mode /* 0: Single extent, 1: Multi extent boot */
|
|
|
|
|
| |
|
|
|
|
|
16 - 19 | load_adr | Load address /* Load below kernel */
|
|
|
|
|
| | Stems from ELF header of boot file.
|
|
|
|
|
| | See below Elf32_Phdr field p_vaddr.
|
|
|
|
|
| |
|
|
|
|
|
20 - 23 | exec_adr | Execution address /* And exec there */
|
|
|
|
|
| | Stems from ELF header of boot file.
|
|
|
|
|
| | See below Elf32_Ehdr field e_entry.
|
|
|
|
|
| |
|
|
|
|
|
24 - 31 | ========== | Boot Map Entry 1
|
|
|
|
|
| |
|
2010-10-14 20:34:32 +00:00
|
|
|
24 - 27 | seg_size | Segment size in file. Blocks of 512 bytes.
|
2010-10-14 15:26:56 +00:00
|
|
|
| | Stems from ELF header of boot file.
|
|
|
|
|
| | (Elf32_Phdr field p_filesz + 511) / 512;
|
|
|
|
|
| |
|
2010-10-14 20:34:32 +00:00
|
|
|
28 - 31 | seg_start | Segment file offset. Blocks 512 bytes.
|
|
|
|
|
| | ISO 9660 LBA of boot file * 4 plus offset
|
|
|
|
|
| | + offset which stems from ELF header of boot file:
|
2010-10-14 15:26:56 +00:00
|
|
|
| | (Elf32_Phdr field p_offset + 511) / 512;
|
|
|
|
|
| |
|
|
|
|
|
32 - 431 | ========== | Boot Map Entries 2 to 51
|
|
|
|
|
| 0 |
|
|
|
|
|
| |
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Elf32_Ehdr gets loaded from boot file byte address 0:
|
|
|
|
|
|
|
|
|
|
Byte Range | Value | Meaning
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
0 - 23 | | ( Magic number, file information )
|
|
|
|
|
| |
|
|
|
|
|
24 - 27 | e_entry | /* Entry point virtual address */
|
|
|
|
|
| = exec_adr | Needed for exec_adr
|
|
|
|
|
| |
|
|
|
|
|
28 - 31 | e_phoff | /* Program header table file offset */
|
|
|
|
|
| | Byte address of Elf32_Phdr
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
|
|
Elf32_Phdr gets loaded from boot file byte_address Elf32_Ehdr.e_phoff :
|
|
|
|
|
Byte Range | Value | Meaning
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
0 - 3 | | ( Segment type )
|
|
|
|
|
| |
|
|
|
|
|
4 - 7 | p_offset | /* Segment file offset */
|
2010-10-14 20:34:32 +00:00
|
|
|
|-> seg_start| Needed for seg_start
|
2010-10-14 15:26:56 +00:00
|
|
|
| |
|
|
|
|
|
8 - 11 | p_vaddr | /* Segment virtual address */
|
2010-10-14 20:34:32 +00:00
|
|
|
| =load_adr | Needed for load_adr
|
2010-10-14 15:26:56 +00:00
|
|
|
| |
|
|
|
|
|
12 - 15 | | (Segment physical address)
|
|
|
|
|
| |
|
|
|
|
|
16 - 19 | p_filesz | /* Segment size in file */
|
2010-10-14 20:34:32 +00:00
|
|
|
|-> seg_size | Needed for seg_size
|
2010-10-14 15:26:56 +00:00
|
|
|
| |
|
2010-11-01 15:05:47 +00:00
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
SUN Disk Label and boot images
|
|
|
|
|
for SUN SPARC
|
|
|
|
|
|
|
|
|
|
Sources:
|
|
|
|
|
cdrtools-2.01.01a77/mkisofs/sunlabel.h
|
|
|
|
|
cdrtools-2.01.01a77/mkisofs/mkisofs.8
|
|
|
|
|
by Joerg Schilling
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
The Disk Label is written to the first 512 bytes of the image. It can mark
|
|
|
|
|
8 partitions (slices ) of which the first contains the ISO image. The other
|
|
|
|
|
7 may contain boot images.
|
|
|
|
|
Words are composed big-endian style.
|
|
|
|
|
|
|
|
|
|
Boot images are provided externally. mkisofs arranges them after the end of
|
|
|
|
|
the ISO image so that each starts at a cylinder boundary (320 kB).
|
|
|
|
|
|
|
|
|
|
There is a mechanism in mkisofs which fills unused partitions by copies of
|
|
|
|
|
their predecessor in the partition table:
|
|
|
|
|
"If the special filename ... is used, the actual and all following
|
|
|
|
|
boot partitions are mapped to the previous partition.
|
|
|
|
|
If mkisofs is called with -G image -B ... all boot partitions are
|
|
|
|
|
mapped to the partition that contains the ISO9660 filesystem."
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Disk Label components:
|
|
|
|
|
|
|
|
|
|
Byte Range | Value | Meaning
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
|
|
|
|
0 - 127 | label | ASCII Label
|
|
|
|
|
| | "CD-ROM Disc with Sun sparc boot created by ..."
|
|
|
|
|
| | mkisofs option -sparc-label
|
|
|
|
|
| |
|
|
|
|
|
128 - 263 | ========== | /* vtoc inclusions from AT&T SVr4 */
|
|
|
|
|
| |
|
|
|
|
|
128 - 131 | 1 | Layout version
|
|
|
|
|
132 - 139 | 0 | /* volume name */
|
|
|
|
|
140 - 141 | 8 | Number of partitions
|
|
|
|
|
| |
|
|
|
|
|
142 - 173 | ========== | 8 partition entries of 4 bytes
|
|
|
|
|
| |
|
|
|
|
|
142 - 145 | ========== | Entry for partition 1
|
|
|
|
|
142 - 143 | 4 | ID tag of partition: 4 = User partition
|
|
|
|
|
144 - 145 | 0x10 | Permissions: 0x10 = read-only
|
|
|
|
|
| |
|
|
|
|
|
146 - 149 | ========== | Entry for partition 2
|
|
|
|
|
146 - 147 | id_tag2 | ID tag of partition:
|
|
|
|
|
| | 0 = unused
|
|
|
|
|
| | 2 = Root partition with boot image
|
|
|
|
|
148 - 149 | perm2 | Permissions:
|
|
|
|
|
| | 0 = unused
|
|
|
|
|
| | 0x10 = read-only (if used)
|
|
|
|
|
| |
|
|
|
|
|
150 - 173 | ========== | Entries for partition 3 to 8.
|
|
|
|
|
| | See above: Entry for partition 2
|
|
|
|
|
| |
|
|
|
|
|
174 - 175 | 0 | Padding
|
|
|
|
|
| |
|
|
|
|
|
176 - 187 | 0 | /* info for mboot */
|
|
|
|
|
| |
|
|
|
|
|
188 - 191 | 0x600ddeee | /* to verify vtoc sanity */
|
|
|
|
|
| |
|
|
|
|
|
192 - 231 | 0 | Reserved
|
|
|
|
|
| |
|
|
|
|
|
232 - 263 | 0 | 8 Timestamps of yet unknown format
|
|
|
|
|
| |
|
|
|
|
|
264 - 419 | 0 | Padding
|
|
|
|
|
| |
|
|
|
|
|
420 - 443 | ========== | Disk properties
|
|
|
|
|
| |
|
|
|
|
|
420 - 421 | 350 | Rotations per minute
|
|
|
|
|
422 - 423 | 2048 | Number of physical cylinders (fixely 640 MB)
|
|
|
|
|
424 - 425 | 0 | /* alternates per cylinder */
|
|
|
|
|
426 - 429 | 0 | /* obsolete */
|
|
|
|
|
430 - 431 | 1 | /* interleave factor */
|
|
|
|
|
432 - 433 | 2048 | Number of data cylinders (fixely 640 MB)
|
|
|
|
|
434 - 435 | 0 | /* # of alternate cylinders */
|
|
|
|
|
436 - 437 | 1 | Number of heads per cylinder (i.e. 1 cyl = 320 kB)
|
|
|
|
|
438 - 439 | 640 | Number of sectors per head (i.e. 1 head = 320 kB)
|
|
|
|
|
440 - 443 | 0 | /* obsolete */
|
|
|
|
|
| |
|
|
|
|
|
444 - 507 | ========== | Partition table
|
|
|
|
|
| |
|
|
|
|
|
444 - 451 | ========== | Partition table entry #1
|
|
|
|
|
| |
|
|
|
|
|
444 - 447 | start_cyl | Start cylinder
|
|
|
|
|
| |
|
|
|
|
|
448 - 451 | num_blocks | Number of blocks in partition
|
|
|
|
|
| |
|
|
|
|
|
452 - 507 | ========== | Partition table entries #2 to #8
|
|
|
|
|
| ... | See above Partition table entry #1
|
|
|
|
|
| |
|
|
|
|
|
508 - 509 | 0xdabe | Magic Number
|
|
|
|
|
| |
|
|
|
|
|
510 - 511 | checksum | The result of exoring 2-byte words 0 to 254
|
|
|
|
|
| |
|
|
|
|
|
---------- | ---------- | ----------------------------------------------------
|
2010-10-14 15:26:56 +00:00
|
|
|
|
2010-10-12 18:24:17 +00:00
|
|
|
|
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
|
|
|
|
>>> ??? HP-PA
|
|
|
|
|
|
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
|
|
|
|
>>> ??? DEC Alpha
|
|
|
|
|
|
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
