linux-kernel - Re: [PATCH] x86: efi/e820 table merge fix

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Message-ID: <4A384914.1090900@zytor.com>
Date:	Tue, 16 Jun 2009 18:38:28 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Huang Ying <ying.huang@...el.com>
CC:	Cliff Wickman <cpw@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"yinghai@...nel.org" <yinghai@...nel.org>
Subject: Re: [PATCH] x86: efi/e820 table merge fix

Huang Ying wrote:
> On Wed, 2009-06-17 at 05:43 +0800, Cliff Wickman wrote:
>> From: Cliff Wickman <cpw@....com>
>> --- linux.orig/arch/x86/kernel/efi.c
>> +++ linux/arch/x86/kernel/efi.c
>> @@ -240,10 +240,35 @@ static void __init do_add_efi_memmap(voi
>>  		unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
>>  		int e820_type;
>>  
>> -		if (md->attribute & EFI_MEMORY_WB)
>> -			e820_type = E820_RAM;
>> -		else
>> +		switch (md->type) {
>> +		case EFI_LOADER_CODE:
>> +		case EFI_LOADER_DATA:
>> +		case EFI_BOOT_SERVICES_CODE:
>> +		case EFI_BOOT_SERVICES_DATA:
>> +		case EFI_CONVENTIONAL_MEMORY:
>> +			if (md->attribute & EFI_MEMORY_WB)
>> +				e820_type = E820_RAM;
>> +			else
>> +				e820_type = E820_RESERVED;
>> +			break;
> 
> Why does BIOS mark memory region without EFI_MEMORY_WB as these types?
> Any example?
> 

Probably not, but if it does, it's broken, and the memory should be
ignored. The original code had the EFI_MEMORY_WB check already, so it
seems prudent to keep it.

	-hpa
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