linux-kernel - Re: [PATCH] x86: make sure wakeup code is below 1M -v2

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Message-ID: <4AFC613D.2060808@kernel.org>
Date:	Thu, 12 Nov 2009 11:25:49 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Pavel Machek <pavel@....cz>
CC:	"Rafael J. Wysocki" <rjw@...k.pl>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Len Brown <lenb@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>
Subject: Re: [PATCH] x86: make sure wakeup code is below 1M -v2

Pavel Machek wrote:
> On Tue 2009-11-10 18:27:23, Yinghai Lu wrote:
>> try to find_e820_area/reserve_early, and call acpi_reserve_memory early
>>
>> to get area is below 1M
> 
>> -	acpi_realmode = (unsigned long)alloc_bootmem_low(WAKEUP_SIZE);
>> +	mem = find_e820_area(0, 1<<20, WAKEUP_SIZE, PAGE_SIZE);
>>  
>> -	if (!acpi_realmode) {
>> +	if (mem == -1L) {
>>  		printk(KERN_ERR "ACPI: Cannot allocate lowmem, S3 disabled.\n");
>>  		return;
>>  	}
> 
> How is it better then old code?

could get range below 1M.

alloc_bootmem_low can not make sure get that below 1M.

init_memory_mapping could use below 1M as page table...

so need to get some buffer for acpi wakeup realmode code.

YH
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