Re: [PATCH] util/grub-mkrescue: specify -iso-level 3 in xorriso options

[Thomas Schmitt]

Hi,

Gerd Hoffmann <kraxel@redhat.com> wrote:
> I doubt the vfat driver of the uefi firmware supports rock ride,
> and that is the driver used to load efi/boot/bootloongarch64.efi
> because grub is not yet loaded ...

xorrisofs option -iso-level 3 has no effect on the FAT filesystem in
the EFI boot image (/efi.img in the grub-mkrescue ISO). xorriso takes this
file as opaque input and just advertises it to the firmware.
Whether grub-mkrescue can represent "bootloongarch64.efi" in FAT is a
matter of the helper programs "mformat" and "mcopy". See line 845 ff. of
util/grub-mkrescue.c . Line 813 ff. shows that it already uses long names
"bootriscv32.efi" and "bootriscv64.efi

The effect of xorrisofs option -iso-level is descibed in the man page of
xorrisofs:

 -iso-level number
     Specify the ISO 9660 version which defines  the  limitations  of
     file  naming  and data file size. The naming restrictions do not
     apply to the Rock Ridge names but only to the low-level ISO 9660
     names.  There are three conformance levels:
     Level  1  allows ISO names of the form 8.3 and file size up to 4
     GiB - 1.
     Level 2 allows ISO names with up to 32 characters and file  size
     up to 4 GiB - 1.
     Level 3  allows ISO names with up to 32 characters and file size
     of up to 400 GiB - 200 KiB. (This size limitation is set by  the
     xorriso  implementation  and  not  by ISO 9660 which would allow
     nearly 8 TiB.)
     Pseudo-level 4 enables production of an additional ISO 9660:1999
     directory tree.

Levels 1 to 3 are specified in ECMA-119, 10 "Levels of interchange".
Pseudo-level 4 is an invention of mkisofs, although it would have been
better to give the ISO 9660:1999 tree an own option, like for Joliet.


Have a nice day :)

Thomas