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Re: [PATCH] x86: make hypervisor build with gcc11

On Wed, May 19, 2021 at 11:40 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
> Gcc 11 looks to make incorrect assumptions about valid ranges that
> pointers may be used for addressing when they are derived from e.g. a
> plain constant. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100680.
> Utilize RELOC_HIDE() to work around the issue, which for x86 manifests
> in at least
> - mpparse.c:efi_check_config(),
> - tboot.c:tboot_probe(),
> - tboot.c:tboot_gen_frametable_integrity(),
> - x86_emulate.c:x86_emulate() (at -O2 only).
> The last case is particularly odd not just because it only triggers at
> higher optimization levels, but also because it only affects one of at
> least three similar constructs. Various "note" diagnostics claim the
> valid index range to be [0, 2⁶³-1].
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Tested-by: Jason Andryuk <jandryuk@xxxxxxxxx>

Needed on Fedora 34.




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