[Bug-xorriso] Re: EFI boot option in mkisofs emulation of xorriso

[Thomas Schmitt]

Hi,

> The ISO works perfectly. I used
> http://www.archlinux.org/packages/community/x86_64/libisoburn/.

Newest releases, as always with Arch. :)

> http://bugs.archlinux.org/task/20419?getfile=5598
> ## Usaully used xorriso command style

There is a typo in "Usaully".

Actually both are mkisofs styles. Plus --efi-boot
as xorriso specific extension.
xorriso has its own option set. But with the
special task of composing bootable single-session
images, people prefer the options which they
know from mkisofs.
For multi-session incremental backup one would
not get happy with mkisofs options, though.

> -eltorito-alt-boot --efi-boot efi/boot/grub2_efi.bin -no-emul-boot

The options -eltorito-alt-boot and -no-emul-boot
are already implied in --efi-boot.
So you may just omit them.

I will implement -e which would need at least
-eltorito-alt-boot as separator from the options
of the BIOS boot image.


> http://bugs.archlinux.org/task/20419
> "The simple (iso-root)/efi/boot/ will work for
>  newer UEFI firmwares (those that contain ISO9660
>  FS driver. The older firmwares need a FAT12 floppy
> image within the iso with a el-torito boot entry
> of Platform id 0xEF apart from the BIOS boot entry
> (Platform ID 0x00).

Interesting. I did not know that there is a EFI
boot facility which does not use the El Torito
Boot record on CD/DVD/Blu-ray media.


If you apply the isohybrid program then the
emerging MBR will not know about EFI, afaik.
Don't the older firmwares need help by the MBR
to find the FAT12 floppy file on an USB stick ?

If i remember right, then the GRUB2 grub-mkrescue
script constructs an ISO image with additional
MBR that can boot from CD/DVD or from USB stick,
both PC-BIOS and EFI.
I have no EFI bootable hardware. So i could only
test BIOS with CD and USB stick. It boots up to
a grub prompt. (The user of grub-mkrescue has to
provide the operating system files.)


> thanks for xorriso and your help.

Don't hesitate to ask for support or new
features.


Have a nice day :)

Thomas