Hi,
Pete Batard wrote:
> I'll just add that I didn't formally test this, since I haven't had a chance
> to locate an ISO with a > 32MB El-Torito image yet.
You can build yourself one:
- Get legacy PC-BIOS boot image isolinux.bin from e.g. a Debian netinst
ISO:
xorriso -osirrox on -indev debian-12.2.0-amd64-netinst.iso \
-extract /isolinux/isolinux.bin isolinux.bin
Or just make a fake file:
dd if=/dev/zero bs=1K count=40 of=isolinux.bin
- Make yourself a FAT filesystem image >= 32 MiB or just some large dummy
file named efi.img :
dd if=/dev/zero bs=1M count=40 of=efi.img
- Pack up as bootable ISO for legacy and for EFI:
xorriso -as mkisofs -v -o test.iso \
-c /boot.cat \
-b /isolinux.bin \
-no-emul-boot -boot-info-table -boot-load-size 4 \
-eltorito-alt-boot
-e /efi.img -no-emul-boot \
./isolinux.bin ./efi.img
With contemporary xorriso expect messages like
xorriso : WARNING : Boot image load size exceeds 65535 blocks of 512 bytes.
Will record 0 in El Torito to extend ESP to end-of-medium.
xorriso : WARNING : EFI boot equipment is provided but no directory /EFI/BOOT
xorriso : WARNING : will emerge in the ISO filesystem. A popular method to
xorriso : WARNING : prepare a USB stick on MS-Windows relies on having in the
xorriso : WARNING : ISO filesystem a copy of the EFI System Partition tree.
ISO image produced: 20683 sectors
If you do not see the warning about "size exceeds 65535 blocks" then
your xorriso might be too old for the purpose.
(https://www.gnu.org/software/xorriso/xorriso-1.5.6.pl02.tar.gz
is the current version, easy to compile, and works without system-wide
installation.)
-----------------------------------------------------------------------
The result is supposed to be reported by:
$ xorriso -indev test.iso -report_el_torito plain
as:
El Torito cat path : /boot.cat
El Torito images : N Pltf B Emul Ld_seg Hdpt Ldsiz LBA
El Torito boot img : 1 BIOS y none 0x0000 0x00 4 20514
El Torito boot img : 2 UEFI y none 0x0000 0x00 0 34
El Torito img path : 1 /isolinux.bin
El Torito img opts : 1 boot-info-table isohybrid-suitable
El Torito img path : 2 /efi.img
Have a nice day :)
Thomas
