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

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Date:	Wed, 17 Jun 2009 09:44:59 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	"H. Peter Anvin" <hpa@...or.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

On Wed, 2009-06-17 at 09:38 +0800, H. Peter Anvin wrote:
> 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.

Maybe we need a real life example for that "fix". And attribute that to
the vendor in comments.

Best Regards,
Huang Ying


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