From: "H. Peter Anvin" <hpa@zytor.com>
To: Andi Kleen <andi@firstfloor.org>, "H.J. Lu" <hjl.tools@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: PATCH] Use -mpreferred-stack-boundary=3 on x86-64 if supported
Date: Sat, 23 Jun 2012 09:17:06 -0700 [thread overview]
Message-ID: <24bd04a1-1702-4d57-af64-af2381992789@email.android.com> (raw)
In-Reply-To: <20120623161324.GS11413@one.firstfloor.org>
To keep gcc from paddong the stack to maintain a nonexistent alignment.
Andi Kleen <andi@firstfloor.org> wrote:
>> This patch uses -mpreferred-stack-boundary=3 on x86-64 if it is
>supported.
>> I have been running 3.4 kernel compiled with this option for weeks.
>
>But why?
>
>All the SSE code in the kernel should adjust manually. And the other
>code doesn't need it.
>
>Besides the entry points do not guarantee alignment.
>
>For the kernel it would be probably more useful to have a attribute
>per function that forces alignment.
>
>-Andi
>--
>ak@linux.intel.com -- Speaking for myself only.
--
Sent from my mobile phone. Please excuse brevity and lack of formatting.
next prev parent reply other threads:[~2012-06-23 16:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-23 16:06 H.J. Lu
2012-06-23 16:13 ` Andi Kleen
2012-06-23 16:17 ` H. Peter Anvin [this message]
2012-06-23 16:49 ` H.J. Lu
2012-06-23 22:57 ` Randy Dunlap
2012-06-23 19:27 ` Andi Kleen
2012-06-23 19:45 ` H. Peter Anvin
2012-06-24 3:13 ` [tip:x86/build] x86-64, gcc: Use -mpreferred-stack-boundary= 3 " tip-bot for H.J. Lu
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