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From:   Florian Weimer <fweimer@redhat.com>
To:     Gavin Shan <gshan@redhat.com>
Cc:     kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
        linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
        pbonzini@redhat.com, maz@kernel.org, oliver.upton@linux.dev,
        andrew.jones@linux.dev, seanjc@google.com,
        mathieu.desnoyers@efficios.com, yihyu@redhat.com,
        shan.gavin@gmail.com
Subject: Re: [PATCH 1/2] KVM: selftests: Make rseq compatible with glibc-2.35
References: <20220809060627.115847-1-gshan@redhat.com>
        <20220809060627.115847-2-gshan@redhat.com>
        <8735e6ncxw.fsf@oldenburg.str.redhat.com>
        <7844e3fa-e49e-de75-e424-e82d3a023dd6@redhat.com>
Date:   Tue, 09 Aug 2022 09:16:33 +0200
In-Reply-To: <7844e3fa-e49e-de75-e424-e82d3a023dd6@redhat.com> (Gavin Shan's
        message of "Tue, 9 Aug 2022 18:45:26 +1000")
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* Gavin Shan:

>> __builtin_thread_pointer doesn't work on all architectures/GCC
>> versions.
>> Is this a problem for selftests?
>> 
>
> It's a problem as the test case is running on all architectures. I think I
> need introduce our own __builtin_thread_pointer() for where it's not
> supported: (1) PowerPC  (2) x86 without GCC 11
>
> Please let me know if I still have missed cases where
> __buitin_thread_pointer() isn't supported?

As far as I know, these are the two outliers that also have rseq
support.  The list is a bit longer if we also consider non-rseq
architectures (csky, hppa, ia64, m68k, microblaze, sparc, don't know
about the Linux architectures without glibc support).

Thanks,
Florian