Branch: refs/heads/master
Home: https://github.com/tianocore/edk2
Commit: 8abbf6d87e68aa6634d63a5e3920ca44e331ddfa
https://github.com/tianocore/edk2/commit/8abbf6d87e68aa6634d63a5e3920ca44e331ddfa
Author: Laszlo Ersek <[email protected]>
Date: 2023-10-19 (Thu, 19 Oct 2023)
Changed paths:
M OvmfPkg/VirtioFsDxe/SimpleFsOpen.c
Log Message:
-----------
OvmfPkg/VirtioFsDxe: tolerate opening an abs. pathname rel. to a reg. file
Referring to a file relative to a regular file makes no sense (or at least
it cannot be implemented consistently with how a file is referred to
relative to a directory). VirtioFsSimpleFileOpen() has enforced this
strictly since the beginning, and a few months ago I reported USWG Mantis
ticket #2367 [1] too, for clearing up the related confusion in the UEFI
spec.
Unfortunately, the shim boot loader contains such a bug [2] [3]. I don't
believe the shim bug is ever going to be fixed. We can however relax the
check in VirtioFsSimpleFileOpen() a bit: if the pathname that's being
opened relative to a regular file is absolute, then the base file is going
to be ignored anyway, so we can let the caller's bug slide. This happens
to make shim work.
Why this matters: UEFI-bootable Linux installer ISOs tend to come with
shim and grub in the embedded (ElTorito) FAT image (ESP). Sometimes you
want to build upstream shim/grub binaries, but boot the same ISO
otherwise. The fastest way for overriding the ESP for this purpose is to
copy its original contents to a virtio filesystem, then overwrite the shim
and grub binaries from the host side. Note that this is different from
direct-booting a kernel (via fw_cfg); the point is to check whether the
just-built shim and grub are able to boot the rest of the ISO.
[1] https://mantis.uefi.org/mantis/view.php?id=2367
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1966973
[3] https://github.com/rhboot/shim/issues/382
Cc: Ard Biesheuvel <[email protected]>
Cc: Gerd Hoffmann <[email protected]>
Cc: Jiewen Yao <[email protected]>
Cc: Jordan Justen <[email protected]>
Signed-off-by: Laszlo Ersek <[email protected]>
Message-Id: <[email protected]>
Reviewed-by: Gerd Hoffmann <[email protected]>
Tested-by: Gerd Hoffmann <[email protected]>
_______________________________________________
edk2-commits mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/edk2-commits
