Clarifications about cylinder size and alignment

This commit is contained in:
2011-03-04 10:46:40 +00:00
parent ad02f33014
commit f85fca7d65
3 changed files with 73 additions and 60 deletions

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@ -9,7 +9,7 @@
.\" First parameter, NAME, should be all caps
.\" Second parameter, SECTION, should be 1-8, maybe w/ subsection
.\" other parameters are allowed: see man(7), man(1)
.TH XORRISO 1 "Mar 02, 2011"
.TH XORRISO 1 "Mar 04, 2011"
.\" Please adjust this date whenever revising the manpage.
.\"
.\" Some roff macros, for reference:
@ -2522,18 +2522,22 @@ The offset value of an ISO image gets preserved when a new session is added.
So the value defined here is only in effect if a new ISO image gets written.
.br
\fBpartition_hd_cyl=\fRnumber gives the number of heads per cylinder for
partition offset. 0 chooses a default value.
partition offset. 0 chooses a default value. Maximum is 255.
.br
\fBpartition_sec_hd=\fRnumber gives the number of sectors per head for
partition offset. 0 chooses a default value.
partition offset. 0 chooses a default value. Maximum is 63.
.br
If the product of partition_sec_hd and partition_hd_cyl is too small to
describe the image size by at most 1024 cylinders, then appropriate values
of partition_hd_cyl are chosen with partition_sec_hd 32 or 63.
The product partition_sec_hd * partition_hd_cyl * 512 is the cylinder size.
It should be divisible by 2048 in order to allow exact alignment.
If it is too small to describe the image size by at most 1024 cylinders,
then appropriate values of partition_hd_cyl are chosen with
partition_sec_hd 32 or 63. If the image is larger than 8,422,686,720 bytes,
then the cylinder size constraints cannot be fulfilled.
.br
\fBpartition_cyl_align=\fRmode controls image size alignment to an integer
number of cylinders. It is prescribed by isohybrid specs and it seems to
please program fdisk.
please program fdisk. Cylinder size must be divisible by 2048.
Images larger than 8,323,596,288 bytes cannot be aligned.
.br
Mode "auto" is default. Alignment by padding happens only with
"isolinux" "partition_table=on".