From: "H. Peter Anvin" <hpa@kernel.org>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Roland McGrath <roland@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
torvalds@linux-foundation.org, jakub@redhat.com,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
x86@kernel.org
Subject: Re: [PATCH 1/2] UNREACHABLE() macro
Date: Fri, 11 Sep 2009 21:43:42 -0700 [thread overview]
Message-ID: <4AAB26FE.7010309@kernel.org> (raw)
In-Reply-To: <20090912054906.22b05848@infradead.org>
On 09/11/2009 08:49 PM, Arjan van de Ven wrote:
> On Fri, 11 Sep 2009 14:55:25 -0700 (PDT)
> Roland McGrath <roland@redhat.com> wrote:
>
>>> That's a bit of a mouthful. Did you consider a runtime probe with
>>> scripts/Kbuild.include's try-run, cc-option, etc?
>>
>> I did not see any precedent in the sources for using those to test for
>> features by compiling particular test sources (i.e. in autoconf
>
> look at the stackprotector flags.. they work this way already.
> It gets done once per kernel build...
>
That works for flags, but not for the presence of builtin functions.
You can't even just try compiling something, since it will turn into an
ordinary function if not present... not obvious until link.
-hpa
next prev parent reply other threads:[~2009-09-12 5:12 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-10 1:59 [PATCH 0/2] __builtin_unreachable Roland McGrath
2009-09-10 2:00 ` [PATCH 1/2] UNREACHABLE() macro Roland McGrath
2009-09-11 20:45 ` Andrew Morton
2009-09-11 20:59 ` Kyle McMartin
2009-09-11 20:59 ` Kyle McMartin
2009-09-11 21:55 ` Roland McGrath
2009-09-12 3:49 ` Arjan van de Ven
2009-09-12 4:43 ` H. Peter Anvin [this message]
2009-09-12 5:30 ` Arjan van de Ven
2009-09-12 5:30 ` Arjan van de Ven
2009-09-12 5:52 ` Andrew Morton
2009-09-12 6:38 ` Jakub Jelinek
2009-09-12 6:38 ` Jakub Jelinek
2009-09-13 20:10 ` H. Peter Anvin
2009-09-10 2:01 ` [PATCH 2/2] x86: BUG(): use UNREACHABLE() Roland McGrath
2009-09-10 2:01 ` Roland McGrath
2009-09-10 4:42 ` [PATCH 0/2] __builtin_unreachable Américo Wang
2009-09-10 6:42 ` H. Peter Anvin
2009-09-10 6:13 ` Jakub Jelinek
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