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Message-Id: <504E196C020000780009A3F9@nat28.tlf.novell.com> Date: Mon, 10 Sep 2012 15:46:36 +0100 From: "Jan Beulich" <JBeulich@...e.com> To: "H. Peter Anvin" <hpa@...or.com> Cc: <mingo@...e.hu>, <tglx@...utronix.de>, <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 2/4] x86/xor: improve XMM register spill/fill >>> On 10.09.12 at 16:05, "H. Peter Anvin" <hpa@...or.com> wrote: > On 09/10/2012 05:38 AM, Jan Beulich wrote: >> +/* >> + * By forcing the alignment beyond the default of 16 bytes, we make the >> + * compiler guarantee the alignment. Passing -mincoming-stack-boundary=3 >> + * (which would have been the better global alternative, as the kernel >> + * never guarantees better stack alignment) isn't permitted on x86-64. >> + */ > > The very latest gcc should handle it, and in fact we compile with > -mstack-alignment=3 if gcc accepts it (if it is not yet upstream it will > be soon.) This affects the validity of this patch. The comment would be stale with that, but the code should still be fine - it would merely over-align the stack in that case (to 32 bytes when 16 would suffice). Or did you spot something else that I'm missing? Also, I can't spot any use of -mstack-alignment= in today's tip's arch/x86/Makefile* - where's that hidden? Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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