From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andi Kleen <ak@muc.de>
Subject: Re: [PATCH] Fixing stack alignment in x86-64 Xen
Date: 18 May 2005 18:14:11 +0200
Message-ID: <20050518161411.GA88141@muc.de>
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Date: Wed, 18 May 2005 18:14:11 +0200
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To: "Nakajima, Jun" <jun.nakajima@intel.com>
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> I think the right thing is to get rsp0 in TSS on a 16-byte boundary by
> getting get_stack_bottom() and get_cpu_user_regs() see the correct
> stack. That will fix the reset_stack_and_jump() as well. It's basically
> what my patch does. 

This means you cannot disable the 16 byte stack alignment in gcc.
Probably does not matter too much today (I guess Xen is not that
bad a stack pig), but in the far future it might come in useful.
Also it would generate smaller code.

-Andi