From: Florian Weimer <fweimer@redhat.com>
To: Tulio Magno Quites Machado Filho <tuliom@ascii.art.br>
Cc: "Lucas A. M. Magalhaes" <lamm@linux.ibm.com>, libc-alpha@sourceware.org
Subject: Re: [PATCH 2/3] powerpc64le: Check HWCAP bits against compiler build flags
Date: Tue, 18 May 2021 18:59:13 +0200 [thread overview]
Message-ID: <874kf05672.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <871racxavs.fsf@linux.ibm.com> (Tulio Magno Quites Machado Filho's message of "Wed, 12 May 2021 11:52:23 -0300")
* Tulio Magno Quites Machado Filho:
> Florian Weimer via Libc-alpha <libc-alpha@sourceware.org> writes:
>
>> I tried to allude in the commit message that this is expected. Maybe I
>> should drop the POWER10 check?
>
> I don't think this is necessary.
> Even if you removed the P10 check, I don't think the P9 check is guaranteed to
> work because when _ARCH_PWR9 is set, the compiler is allowed to use P9
> instructions in this function before the test is executed.
>
> I think this patch is trying to improve the error message to the user.
>
> With that said, it doesn't hurt to copy your explanation as a source code
> comment, i.e.:
>
> /* This approach does not work for the POWER10 because the bootstrap
> relocation already uses PCREL instructions, so the detection code does
> not actually run. */
What about this instead?
/* This check is not actually reached when building for POWER10 and
running on POWER9 because there are faulting PCREL instructions
before this point. */
Thanks,
Florian
next prev parent reply other threads:[~2021-05-18 16:59 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-06 12:30 [PATCH 0/3] Checking HWCAP bits against compiler flags Florian Weimer
2021-05-06 12:30 ` [PATCH 1/3] elf: Add hook for checking HWCAP bits after auxiliary vector parsing Florian Weimer
2021-05-12 7:43 ` Stefan Liebler
2021-05-06 12:30 ` [PATCH 2/3] powerpc64le: Check HWCAP bits against compiler build flags Florian Weimer
2021-05-11 21:12 ` Lucas A. M. Magalhaes
2021-05-12 8:27 ` Florian Weimer
2021-05-12 14:50 ` Lucas A. M. Magalhaes
2021-05-12 14:52 ` Tulio Magno Quites Machado Filho
2021-05-12 17:27 ` Florian Weimer
2021-05-12 19:24 ` Tulio Magno Quites Machado Filho
2021-05-18 16:59 ` Florian Weimer [this message]
2021-05-18 17:26 ` Tulio Magno Quites Machado Filho
2021-05-18 17:41 ` Florian Weimer
2021-05-06 12:30 ` [PATCH 3/3] s390x: Check HWCAP bits against compiler flags Florian Weimer
2021-05-12 7:43 ` Stefan Liebler
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