From 654ff82345802f7e05a3ed07bcb9236731c77f8c Mon Sep 17 00:00:00 2001 From: Thomas Schmitt Date: Mon, 18 Nov 2013 13:22:17 +0100 Subject: [PATCH] Mentioned boot image address in newer GRUB2 MBR --- doc/boot_sectors.txt | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/doc/boot_sectors.txt b/doc/boot_sectors.txt index bf02337..29395a4 100644 --- a/doc/boot_sectors.txt +++ b/doc/boot_sectors.txt @@ -1351,12 +1351,21 @@ Sources: Mailing list conversations with Vladimir Serbinenko. -The MBR file that is used with GRUB2 script grub-mkrescue needs only a -partition table entry which describes the image size. +The MBR file that is used with older versions of GRUB2 script grub-mkrescue +needs only a partition table entry which describes the image size. +Newer versions get patched by the block address of the content of the first +El Torito boot image. See grub-mkrescue use of xorrisofs option --grub2-mbr. Byte Range | Value | Meaning ---------- | ---------- | ---------------------------------------------------- - 0 - 445 | = opaque = | GRUB2 machine code provided by MBR template + 0 - 431 | = opaque = | GRUB2 machine code provided by MBR template + | | + 432 - 439 | bootimg_adr| With newer versions of grub-mkrescue: + | | Block address of the start of the boot image file + | | content plus 4. Block size is 512. + | | 64 bit Little-endian. + | | + 440 - 445 | = opaque = | provided by MBR template | | 446 - 509 | ========== | Partition table | |