Bug#997907: linux-image-arm64: CONFIG_EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER unset in 5.14 kernel
On Tue, 23 Nov 2021 at 06:12, Salvatore Bonaccorso <carnil@debian.org> wrote:
>
> Hi Vincent,
>
> On Fri, Nov 19, 2021 at 10:04:57PM +0100, Vincent Blut wrote:
> > Hi,
> >
> > Le 2021-10-26 17:33, Zameer Manji a écrit :
> > > On Tue, Oct 26, 2021 at 5:05 PM Vincent Blut <vincent.debian@free.fr> wrote:
> > >
> > > > Control: reassign -1 src:linux
> > > >
> > > > Hi,
> > > >
> > > > Le 2021-10-26 20:44, Zameer Manji a écrit :
> > > > > Package: linux-image-arm64
> > > > > Version: 5.14.9-2
> > > > > Severity: important
> > > > >
> > > > > Dear Maintainer,
> > > > >
> > > > > In bullseye, version 5.10.70-1 has the
> > > > CONFIG_EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER
> > > > > kernel configuration set to 'y'. In bookworm it is unset which disable
> > > > this feature.
> > > > >
> > > > > This kernel configuration parameter allows for the EFI stub of the
> > > > kernel to
> > > > > parse and use a 'initrd=' parameter to set up an initrd when booting
> > > > from EFI.
> > > > > Boot loaders like 'systemd-boot' or 'refind' set this parameter if
> > > > configured
> > > > > to pass an initrd. If the kernel configuration parameter is unset, the
> > > > > `initrd=` paramater is ignored, and can result in an unbootable system
> > > > because
> > > > > the initrd has not setup the root filesystem.
> > > > >
> > > > > Without the kernel configuaration set, it is not possible to use
> > > > 'systemd-boot'
> > > > > or 'refind' on arm64 as both of these bootloaders assume the kernel will
> > > > > handle the 'initrd=' flag and setup the initrd.
> > > > >
> > > > > Please consider enabling CONFIG_EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER on
> > > > > arm64 so using 'systemd-boot' or 'refind' can continue to work. Until
> > > > these
> > > > > bootloaders have been updated to use an alternative method of passing the
> > > > > initrd to the EFI stub, it is not possible to have a booting system.
> > > >
> > > > Except on X86, EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER is no longer enabled
> > > > by
> > > > default. Please see [1] for some details.
> > > >
> > > > Cheers,
> > > > Vincent
> > > >
> > > > [1]
> > > > https://gitlab.com/linux-kernel/stable/-/commit/6edcf9dc2e1aff3aa1f5a69ee420fb30dd0e968a
> > > >
> > >
> > > Hello Vincent,
> > >
> > > I see and understand the rationale of upstream to deprecate this
> > > functionality.
> > > >From the commit you linked I see another commit [0] which says:
> > >
> > > > Loading an initrd passed via the kernel command line is deprecated: it
> > > > is limited to files that reside in the same volume as the one the kernel
> > > > itself was loaded from, and we have more flexible ways to achieve the
> > > > same. So make it configurable so new architectures can decide not to
> > > > enable it.
> > >
> > > I assume the 'more flexible ways' to do the same is referencing this
> > > feature [1]
> > > which is indeed more flexible. The problem is that the firmware/bootloader
> > > must
> > > support this new functionality, by populating the right EFI file with the
> > > right GUID.
> > >
> > > As far as I can see on arm64 there are three EFI bootloaders:
> > > * GRUB2
> > > * systemd-boot
> > > * refind
> > >
> > > Both systemd-boot and refind do not yet support this new mechanism,
> > > although I see
> > > that systemd has some unreleased code [2] to support the new way. I have
> > > not been
> > > able to test GRUB2 but my understanding is that this new method is still
> > > under active
> > > development [3].
> > >
> > > The problem is that upstream has deprecated this functionality by assuming
> > > the only
> > > active use was x86, but was completely possible to use it on arm64 (it
> > > works fine for me
> > > on bullseye). Since EFI bootloaders have not yet implemented the new way,
> > > and still
> > > rely on this deprecated method on all architectures, it results in
> > > unbootable systems
> > > on arm64.
> > >
> > > I would 100% think this should remain disabled on arm64 if most EFI
> > > bootloaders
> > > supported the new way, but unfortunately they do not.
> > >
> > > I hope you would consider enabling this kernel configuration for arm64
> > > until EFI
> > > bootloaders catch up to the recommended way.
> > >
> > >
> > > [0]
> > > https://gitlab.com/linux-kernel/stable/-/commit/cf6b83664895a5c7e97710df282e220bd047f0f5
> > > [1]
> > > https://gitlab.com/linux-kernel/stable/-/commit/ec93fc371f014a6fb483e3556061ecad4b40735c
> > > [2]
> > > https://github.com/systemd/systemd/commit/a6089431d52adda93eec251a3df0dffa1fe0661a#diff-76eb4030e88f340c9133388f17c65774b0f17a0a8105500978f6ce18ca1deb5a
> > > [3] https://www.mail-archive.com/grub-devel@gnu.org/msg32272.html
> >
> > Salvatore, I tend to agree with Zameer. I think we should explicitly enable
> > EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER until the support for loading initrd
> > from a device path is widespread among bootloaders.
>
> Yeah I guess it makes sense and understand. Before doing the switch
> and re-enabling it explicitly, let's ask Ard if there are known plans for
> !X86 and say so for example arm64 as well to revert the default
> upstream. The more we can follow those upstream the better for us :)
>
> Ard, this is about https://bugs.debian.org/997907 on non X86,
> specifically for arm64.
>
Hello all,
I don't see a reason to revert the default upstream. The feature
remains deprecated (and in the longer term, the EFI handover protocol
may be deprecated and removed as well), so the earlier the bootloaders
adapt, the better it is.
In the meantime, keeping it enabled in the distros for arm64 makes
sense because there is an established installed base. But that doesn't
mean this should be the upstream default.
--
Ard.
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