Re: [PATCH] [20/45] x86_64: Use 8 byte stack alignment when possible

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To: Andi Kleen <ak@...>
Cc: <patches@...>, <linux-kernel@...>
Date: Friday, September 21, 2007 - 6:52 pm

On Sat, Sep 22, 2007 at 12:34:31AM +0200, Andi Kleen wrote:
 > On Friday 21 September 2007 23:13, Dave Jones wrote:
 > > On Fri, Sep 21, 2007 at 10:45:02PM +0200, Andi Kleen wrote:
 > >  > Kernel doesn't use SSE2, so it doesn't need 16 byte alignment. Also
 > >  > the stack can be already unaligned so letting the compiler align
 > >  > is useless. This may make some stack frames smaller.
 > >  > Only works with very recent gcc 4.3
 > >
 > > My gcc 4.1.2 from Fedora 7 (with who knows what backported)
 > > references this in its manpage. How was it broken before 4.3 ?
 > 
 > Try it. It is rejected by the compiler in 64bit mode.

Ah yes, it fails if not between 4 & 12, but the call cc-option
catches that.  Looks fine to me.

	Dave

-- 
http://www.codemonkey.org.uk
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Messages in current thread:
[PATCH] [0/45] x86 2.6.24 patches review I, Andi Kleen, (Fri Sep 21, 4:44 pm)
[PATCH] [41/45] i386: remove unnecessary code, Andi Kleen, (Fri Sep 21, 4:45 pm)
[PATCH] [35/45] i386: make some variables static, Andi Kleen, (Fri Sep 21, 4:45 pm)
[PATCH] [33/45] i386: es7000 minor cleanups, Andi Kleen, (Fri Sep 21, 4:45 pm)
Re: [PATCH] [32/45] x86_64: hide cond_syscall behind __KERNE..., Christoph Hellwig, (Sat Sep 22, 5:30 am)
[PATCH] [31/45] i386: make struct apic_probe static, Andi Kleen, (Fri Sep 21, 4:45 pm)
[PATCH] [25/45] x86_64: remove sync_Arb_IDs, Andi Kleen, (Fri Sep 21, 4:45 pm)
Re: [PATCH] [24/45] x86: Introduce frame_pointer() and stack..., Christoph Hellwig, (Sat Sep 22, 5:26 am)
Re: [PATCH] [20/45] x86_64: Use 8 byte stack alignment when ..., Dave Jones, (Fri Sep 21, 6:52 pm)
[PATCH] [4/45] i386: Rewrite sched_clock, Andi Kleen, (Fri Sep 21, 4:44 pm)
[PATCH] [2/45] x86: constify stacktrace_ops, Andi Kleen, (Fri Sep 21, 4:44 pm)
[PATCH] [1/45] x86: misc. constifications, Andi Kleen, (Fri Sep 21, 4:44 pm)