linux-kernel - Re: [PATCH] x86: Reserve legacy VGA MMIO area for x86_64 as well as x86

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Date:	Wed, 07 Apr 2010 16:43:44 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Yinghai <yinghai.lu@...cle.com>
CC:	Bjorn Helgaas <bjorn.helgaas@...com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, linux-pci@...r.kernel.org,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	Andy Isaacson <adi@...apodia.org>,
	Thomas Renninger <trenn@...e.de>
Subject: Re: [PATCH] x86: Reserve legacy VGA MMIO area for x86_64 as well
 as x86_32

On 04/07/2010 03:45 PM, Yinghai wrote:
> 
> It seem another thread, erission has one model without VGA, and they use that area for other device MMIO.
> 
> current for 64bit, We remove [0xa0000, 0x100000) from e820 map if those area is E820_RAM.
> 

Removing is not the same thing as reserving!

A range with no type in E820 is address space available for allocation;
whereas in order to be reserved, it should be E820_RESERVED.

> in e820_reserve_resources(), kernel will reserve range < 1M according to e820 map.
> that is before pci BAR is claimed.
> 
> or you can add
> boot_params.screen_info.orig_video_isVGA == 1
> or double check scan pci tree to see if video is there or not

Perhaps boot_params.screen_info.orig_video_isVGA != 1 because he's not
booting in a text mode?
	
	-hpa

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