EFI boot fails when CONFIG_DEBUG_INFO_BTF=y on arm64

EFI boot fails when CONFIG_DEBUG_INFO_BTF=y on arm64

[Vitaly Chikunov]

Hi,

We have boot test using OVMF/AAVMF EFI firmware on aarch64 in qemu. When
we try to build kernel with `CONFIG_DEBUG_INFO_BTF=y' (pahole v1.20)
previously successful EFI boot test fails with:

  EFI stub: ERROR: Failed to relocate kernel
  EFI stub: ERROR: Failed to relocate kernel

Without EFI it boots normally. On other our architectures (such as
arm32, i586, powerpc, x86_64) it boots normally too (all without EFI
boot, but x86_64 is also successfully tested with OVMF EFI boot).

This is tested on 5.4.97, but I can try 5.10.15 if needed.

Thanks,

Re: EFI boot fails when CONFIG_DEBUG_INFO_BTF=y on arm64

[Andrii Nakryiko]

On Thu, Feb 11, 2021 at 3:44 PM Vitaly Chikunov <vt@altlinux.org> wrote:
>
> Hi,
>
> We have boot test using OVMF/AAVMF EFI firmware on aarch64 in qemu. When
> we try to build kernel with `CONFIG_DEBUG_INFO_BTF=y' (pahole v1.20)
> previously successful EFI boot test fails with:
>
>   EFI stub: ERROR: Failed to relocate kernel
>   EFI stub: ERROR: Failed to relocate kernel
>
> Without EFI it boots normally. On other our architectures (such as
> arm32, i586, powerpc, x86_64) it boots normally too (all without EFI
> boot, but x86_64 is also successfully tested with OVMF EFI boot).

So this seems like an arm64-specific issue? Is it possible to get any
help from someone familiar with arm64 specifics to find out what
exactly causes this problem? We use `pahole -J` to "implant" .BTF into
vmlinux.o, but later rely on vmlinux loader scripts to have a loadable
.BTF section. The problem might happen somewhere along those steps. I
don't think I can be of much help here without a bit more information
(and seems like no one else on this list came up with any suggestions
as well).

>
> This is tested on 5.4.97, but I can try 5.10.15 if needed.
>
> Thanks,
>

Re: EFI boot fails when CONFIG_DEBUG_INFO_BTF=y on arm64

[Vitaly Chikunov]

Andrii,

On Mon, Feb 22, 2021 at 05:30:09PM -0800, Andrii Nakryiko wrote:
> On Thu, Feb 11, 2021 at 3:44 PM Vitaly Chikunov <vt@altlinux.org> wrote:
> >
> > Hi,
> >
> > We have boot test using OVMF/AAVMF EFI firmware on aarch64 in qemu. When
> > we try to build kernel with `CONFIG_DEBUG_INFO_BTF=y' (pahole v1.20)
> > previously successful EFI boot test fails with:
> >
> >   EFI stub: ERROR: Failed to relocate kernel
> >   EFI stub: ERROR: Failed to relocate kernel
> >
> > Without EFI it boots normally. On other our architectures (such as
> > arm32, i586, powerpc, x86_64) it boots normally too (all without EFI
> > boot, but x86_64 is also successfully tested with OVMF EFI boot).
> 
> So this seems like an arm64-specific issue? Is it possible to get any
> help from someone familiar with arm64 specifics to find out what
> exactly causes this problem? We use `pahole -J` to "implant" .BTF into
> vmlinux.o, but later rely on vmlinux loader scripts to have a loadable
> .BTF section. The problem might happen somewhere along those steps. I
> don't think I can be of much help here without a bit more information
> (and seems like no one else on this list came up with any suggestions
> as well).

Thanks for the reply! After some experiments and debugging today it's
turned out that problem is low default memory size for qemu. When
increased to `-m 512` it booted good. Thereby, now we can enable BTF for
aarch64 too.

Vitaly,

> 
> >
> > This is tested on 5.4.97, but I can try 5.10.15 if needed.
> >
> > Thanks,
> >