Date: Tue, 30 Jan 2007 11:10:58 -0800
From: Andrew Morton <akpm@osdl.org>
To: =?ISO-8859-1?B?RnLpZOlyaWM=?= Riss <frederic.riss@gmail.com>,
       Matt Domsch <Matt_Domsch@dell.com>
Cc: linux-kernel@vger.kernel.org, artiom.myaskouvskey@intel.com,
       bjorn.helgaas@hp.com, Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] EFI x86: pass firmware call parameters on the stack
Message-Id: <20070130111058.db191e07.akpm@osdl.org>
In-Reply-To: <1170183678.21603.73.camel@funkylaptop>
References: <1170183678.21603.73.camel@funkylaptop>
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On Tue, 30 Jan 2007 20:01:18 +0100
Fr?d?ric Riss <frederic.riss@gmail.com> wrote:

> 
> When calling into an EFI firmware, the parameters need to be passed on
> the stack. The recent change to use -mregparm=3 breaks x86 EFI support.
> This patch is needed to allow the new Intel-based Macs to suspend to ram
> when run in EFI mode (efi.get_time is called during the suspend phase).
> 
> Signed-off-by: Frederic Riss <frederic.riss@gmail.com>
> 
> ---
> 
> [As I couldn't find an official maintainer for the linux/efi.h file and
> the file header is quite old, I'm Cc:ing the last 2 commiters.]

Matt normally looks after EFI.

> This patch fixes the issue for x86, but the file is also used by IA64. I
> would have used asmlinkage to force arguments on the stack, but it has a
> special meaning on IA64, thus I used a raw regparm(0) GCC attribute.
> This attribute is documented only for x86, I hope it has no side effect
> on other archs.

hm, this sounds like a fairly serious problem.  Has this been runtime
tested on ia64 and x86_64>


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