linux-kernel - Re: [PATCH] x86: trim ACPI sleep stack buffer

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Date:	Thu, 09 Oct 2008 13:19:32 -0400 (EDT)
From:	Len Brown <lenb@...nel.org>
To:	Matt Mackall <mpm@...enic.com>
Cc:	Pavel Machek <pavel@...e.cz>, Ingo Molnar <mingo@...e.hu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-acpi@...r.kernel.org
Subject: Re: [PATCH] x86: trim ACPI sleep stack buffer

applied to acpi-test.

thanks Matt,
-Len

On Thu, 9 Oct 2008, Matt Mackall wrote:

> On Thu, 2008-10-09 at 10:56 +0200, Pavel Machek wrote:
> > > We've got:
> > > 
> > > #if defined(CONFIG_SMP) && defined(CONFIG_64BIT)
> > > static char temp_stack[10240];
> > > #endif
> > > 
> > > and:
> > > 
> > > #ifdef CONFIG_SMP
> > >         stack_start.sp = temp_stack + 4096;
> > > #endif
> > > 
> > > ..which suggests we use at most 4k of the stack?
> > 
> > I guess someone (probably me) was "playing it safe" -- not exactly
> > remembering if stack grows down or up. I guess it should be safe to
> > change it... will do that.
> > 									Pavel
> 
> I've already got a patch, I was just wondering if there was some obscure
> architectural reason for it that I wasn't aware of.
> 
> 
> x86: trim ACPI sleep stack buffer
> 
> x86_64 SMP suspend to RAM uses a 10k temporary stack for saving the
> kernel state, but only 4k of it is used. Shrink it to 4k.
> 
> Signed-off-by: Matt Mackall <mpm@...enic.com>
> 
> diff -r 73d55a1b6c10 arch/x86/kernel/acpi/sleep.c
> --- a/arch/x86/kernel/acpi/sleep.c	Wed Oct 08 14:48:45 2008 -0500
> +++ b/arch/x86/kernel/acpi/sleep.c	Thu Oct 09 11:51:54 2008 -0500
> @@ -21,7 +21,7 @@
>  static unsigned long acpi_realmode;
>  
>  #if defined(CONFIG_SMP) && defined(CONFIG_64BIT)
> -static char temp_stack[10240];
> +static char temp_stack[4096];
>  #endif
>  
>  /**
> 
> -- 
> Mathematics is the supreme nostalgia of our time.
> 
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