From: Andi Kleen <andi@firstfloor.org>
To: "Török Edwin" <edwintorok@gmail.com>
Cc: "Thomas Gleixner mingo@redhat.com" <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: gcc-4.3 considers unaligned accesses on X86 as undefined
Date: 26 Mar 2008 06:30:17 +0100 [thread overview]
Message-ID: <87d4pinjbq.fsf@basil.nowhere.org> (raw)
In-Reply-To: <47E965BD.7010604@gmail.com>
Török Edwin <edwintorok@gmail.com> writes:
> At -O3 it generates vectorized code that _relies_ on the fact that
> pointers are always aligned (unless you use packed attributes, etc.),
> and the resulting code crashes if the pointer is unaligned. (-O3 -msse
> on 32-bit, and simply -O3 on 64-bit since -msse is default)
The 2.6 kernel disables SSE and MMX code generation explicitely.
2.4 should be also safe unless someone misguided recompiles it with -O3.
-Andi
prev parent reply other threads:[~2008-03-26 5:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-25 20:51 gcc-4.3 considers unaligned accesses on X86 as undefined Török Edwin
2008-03-25 20:56 ` H. Peter Anvin
2008-03-25 21:11 ` Alan Cox
2008-03-26 5:30 ` Andi Kleen [this message]
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