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SubjectRe: [PATCH AUTOSEL 4.19 133/191] efi: honour memory reservations passed via a linux specific config table
On Sun, 10 Nov 2019 at 13:27, Sasha Levin <> wrote:
> On Sun, Nov 10, 2019 at 08:33:47AM +0100, Ard Biesheuvel wrote:
> >On Sun, 10 Nov 2019 at 03:44, Sasha Levin <> wrote:
> >>
> >> From: Ard Biesheuvel <>
> >>
> >> [ Upstream commit 71e0940d52e107748b270213a01d3b1546657d74 ]
> >>
> >> In order to allow the OS to reserve memory persistently across a
> >> kexec, introduce a Linux-specific UEFI configuration table that
> >> points to the head of a linked list in memory, allowing each kernel
> >> to add list items describing memory regions that the next kernel
> >> should treat as reserved.
> >>
> >> This is useful, e.g., for GICv3 based ARM systems that cannot disable
> >> DMA access to the LPI tables, forcing them to reuse the same memory
> >> region again after a kexec reboot.
> >>
> >> Tested-by: Jeremy Linton <>
> >> Signed-off-by: Ard Biesheuvel <>
> >> Signed-off-by: Sasha Levin <>
> >
> >NAK
> >
> >This doesn't belong in -stable, and I'd be interested in understanding
> >how this got autoselected, and how I can prevent this from happening
> >again in the future.
> It was selected because it's part of a fix for a real issue reported by
> users:

For my understanding, are you saying your AI is reading launchpad bug
reports etc? Because it is marked AUTOSEL.


That pages mentions

2 upstream patch series are required to fix this:
https://<email address hidden>/msg10328.html
Which provides an EFI facility consumed by:
There were also some follow-on fixes to deal with ARM-specific
problems associated with this usage:

and without the other patches, we only add bugs and don't fix any.

> Besides ubuntu, it is also carried by:
> CentOS:
> As a way to resolve the reported bug.

Backporting a feature/fix like this requires careful consideration of
the patches involved, and doing actual testing on hardware.

> Any reason this *shouldn't* be in stable?

Yes. By itself, it causes crashes at early boot and does not actually
solve the problem.

> I'm aware that there might be
> dependencies that are not obvious to me, but the solution here is to
> take those dependencies as well rather than ignore the process
> completely.

This is not a bugfix. kexec/kdump never worked correctly on the
hardware involved, and backporting a feature like that goes way beyond
what I am willing to accept for stable backports affecting the EFI

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