Re: Bug#927892: grub-ieee1275-bin: Please add bootinfo.txt for sparc and sparc64
On 27/04/2019 19:26, Thomas Schmitt wrote:
> Hi,
>
> xorriso-wise, the debian-10.0-sparc64-grub-NETINST-1.iso looks ok:
>
> $ xorriso -indev debian-10.0-sparc64-grub-NETINST-1.iso \
> -report_system_area plain
> ...
> Volume id : 'Debian 10.0 sparc64 n'
> System area options: 0x0000000c
> System area summary: SUN-SPARC-Disk-Label
> ISO image size/512 : 443640
> SUN SPARC disklabel: CD-ROM Disc with Sun sparc boot created by libisofs
> SUN SPARC secs/head: 640
> SUN SPARC heads/cyl: 1
> SUN SPARC partmap : N IdTag Perms StartCyl NumBlocks
> SUN SPARC partition: 1 0x0004 0x0010 0 443640
> SUN SPARC partition: 2 0x0002 0x0010 0 443640
> SUN SPARC partition: 3 0x0002 0x0010 0 443640
> SUN SPARC partition: 4 0x0002 0x0010 0 443640
> SUN SPARC partition: 5 0x0002 0x0010 0 443640
> SUN SPARC partition: 6 0x0002 0x0010 0 443640
> SUN SPARC partition: 7 0x0002 0x0010 0 443640
> SUN SPARC partition: 8 0x0002 0x0010 0 443640
> SPARC GRUB2 core : 1748992 453104
> SPARC GRUB2 path : /boot/core.img
>
> xorriso reports /boot/core.img as "SPARC GRUB2 path", because it was
> recognized as comming from the same disk inode as /boot/grub/core.img
> and thus shares the content blocks with it:
>
> $ xorriso -indev debian-10.0-sparc64-grub-NETINST-1.iso \
> -find /boot/core.img -exec report_lba -- \
> -find /boot/grub/core.img -exec report_lba --
> ...
> Report layout: xt , Startlba , Blocks , Filesize , ISO image path
> File data lba: 0 , 854 , 222 , 453104 , '/boot/core.img'
> Report layout: xt , Startlba , Blocks , Filesize , ISO image path
> File data lba: 0 , 854 , 222 , 453104 , '/boot/grub/core.img'
>
> So all is well. Except the nearly zero content of bytes 512 to 767 of
> the ISO.
One interesting point: the local man page for genisoimage on my Debian stretch
machine states this:
-G generic_boot_image
Specifies the path and filename of the generic boot image to be used
when making a generic bootable CD. The boot image will be placed on
the first 16 sectors of the CD, before the ISO9660 primary volume
descriptor. If this option is used together with -sparc-boot, the Sun
disk label will overlay the first 512 bytes of the generic boot image.
This implies that we need to pad cdboot.img with an initial 512 bytes which matches
what Thomas said in one of his earlier emails:
"grub-mkrescue opens cdboot.img for reading and the image file for -G
for writing and truncates it to 0 length. Then it writes 512 zero bytes,
reads 512 bytes from cdboot.img and writes them to the -G image file."
ATB,
Mark.
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