On 10/19/23 08:28, Gerd Hoffmann wrote: > On Wed, Oct 18, 2023 at 07:24:34PM +0200, Laszlo Ersek wrote: >> 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 <ardb+tianoc...@kernel.org> >> Cc: Gerd Hoffmann <kra...@redhat.com> >> Cc: Jiewen Yao <jiewen....@intel.com> >> Cc: Jordan Justen <jordan.l.jus...@intel.com> >> Signed-off-by: Laszlo Ersek <ler...@redhat.com> > > Reviewed-by: Gerd Hoffmann <kra...@redhat.com> > Tested-by: Gerd Hoffmann <kra...@redhat.com>
Merged via <https://github.com/tianocore/edk2/pull/4930>; commit 8abbf6d87e68. Thanks! Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#109804): https://edk2.groups.io/g/devel/message/109804 Mute This Topic: https://groups.io/mt/102044004/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/leave/9847357/21656/1706620634/xyzzy [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
