From: Andrew Morton <akpm@linux-foundation.org>
To: "H. Peter Anvin" <hpa@kernel.org>
Cc: Arjan van de Ven <arjan@infradead.org>,
Roland McGrath <roland@redhat.com>,
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 22:52:28 -0700 [thread overview]
Message-ID: <20090911225228.e67460f5.akpm@linux-foundation.org> (raw)
In-Reply-To: <4AAB26FE.7010309@kernel.org>
On Fri, 11 Sep 2009 21:43:42 -0700 "H. Peter Anvin" <hpa@kernel.org> wrote:
> 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.
>
Use -Wall -Werror and if the compiler doesn't know about
__builtin_unreachable() it will error out.
next prev parent reply other threads:[~2009-09-12 5:55 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
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 [this message]
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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