Re: [PATCH] util/grub-mkrescue: use capitalised paths for removable EFI images

[Thomas Schmitt]

Hi,

Mingcong Bai wrote:
> I was testing for loongarch64-efi. As noted in the commit message, I
> found that Loongson's firmware incapable of handling non-upper-case EFI
> boot paths

If no test reports emerge about other platforms, then i would consider to
reduce the patch to what was tested and is really needed with real-world
firmware.

The potential xorriso failure would only show up with x86 platforms.
So reducing the patch to the smallest needed change would be the best way
to avoid such mishaps with untested platforms.


> with the boot.efi change removed, there shouldn't be any more
> error - right?

I see no other change in your patch which would influence the ISO 9660
filesystem tree and the possible HFS+ tree. Thus i think it should be
safe.

Note that the name "boot.efi" gets used for two occasions: Once it gets
into the FAT filesystem and once into the ISO 9660 / HFS+ filesystem.
The comments in the code and my conversations with Vladimir Serbinenko
indicate that both times it is for x86 Macs. Those which read HFS+ are
probably quite old.
The FAT filesystem image becomes a data file in the ISO filesystem.
xorriso will not peek into the FAT filesystem. So renaming the "boot.efi"
which goes into FAT will not cause the need for changes about the xorriso
options.

(File names in the ISO 9660 fileystem are case-insensitive for the dull
ISO names, but case-sensitive for the Rock Ridge extensions which augment
the ISO 9660 filesystem to comply with X/Open specs. The HFS+ tree, which
shares data file content with the ISO tree, is case-insensitive.
Since the "xo" in the name "xorriso" stands for X/Open and the "rr" stands
for Rock Ridge, xorriso is case-sensitive with its file path arguments.)


> > - The new name "BOOTx64.EFI" isn't actually all uppercase.

> Indeed, but I'm no one to argue with the specifications.

Avoiding to change it would elegantly avoid the question whether we know
better than the specs.
Else you would possibly have to change the patch title to something like:
  "use paths for removable EFI images as prescribed by UEFI"


> non-upper-case EFI boot paths (which grub-install happens to evade,
> as it creates upper-case paths and filenames in the first place)

So you could call the patch a unification of name habits between
grub-install and grub-mkrescue. Maybe this attracts more testers for
the other platforms.


Have a nice day :)

Thomas