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Date:   Tue, 14 Sep 2021 13:30:46 -0700
From:   Sami Tolvanen <>
To:     Nick Desaulniers <>
Cc:     X86 ML <>, Kees Cook <>,
        Josh Poimboeuf <>,
        Peter Zijlstra <>,
        Nathan Chancellor <>,
        Sedat Dilek <>,,
        LKML <>,
        clang-built-linux <>
Subject: Re: [PATCH v3 11/16] x86/purgatory: Disable CFI

On Tue, Sep 14, 2021 at 1:02 PM Nick Desaulniers
<> wrote:
> On Tue, Sep 14, 2021 at 12:11 PM Sami Tolvanen <> wrote:
> >
> > Disable CONFIG_CFI_CLANG for the stand-alone
> >
> > Signed-off-by: Sami Tolvanen <>
> I kind of prefer the existing convention that has explicit guards on
> which configs may introduce which flags that are problematic. This
> patch is ok as is, but it kind of makes this Makefile more
> inconsistent.  I would prefer we had the explicit checks.

The Makefile does already use DISABLE_STACKLEAK_PLUGIN in a similar
way, but I don't have a strong preference here. I can move this into
an ifdef if it makes things cleaner.

> Does CFI actually do any instrumentation in these object files? I
> guess issues in purgatory cause silent/hard to debug kexec failures?

The compiler shouldn't add any actual CFI instrumentation here right
now, but I would prefer to avoid issues in future.


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