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

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Message-ID: <4911F71203A09E4D9981D27F9D83085803123361@orsmsx503.amr.corp.intel.com>
Date:	Thu, 9 Oct 2008 10:23:47 -0700
From:	"Moore, Robert" <robert.moore@...el.com>
To:	Len Brown <lenb@...nel.org>, 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" <linux-acpi@...r.kernel.org>
Subject: RE: [PATCH] x86: trim ACPI sleep stack buffer

Sounds like you need a

#define DEFAULT_STACK_SIZE 4096

Somewhere.


>-----Original Message-----
>From: linux-acpi-owner@...r.kernel.org [mailto:linux-acpi-
>owner@...r.kernel.org] On Behalf Of Len Brown
>Sent: Thursday, October 09, 2008 10:20 AM
>To: Matt Mackall
>Cc: Pavel Machek; Ingo Molnar; Linux Kernel Mailing List; 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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