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

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Message-ID: <4BBD6306.9010608@zytor.com>
Date:	Wed, 07 Apr 2010 22:00:54 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andy Isaacson <adi@...apodia.org>
CC:	Yinghai <yinghai.lu@...cle.com>,
	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,
	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 05:19 PM, Andy Isaacson wrote:
> On Wed, Apr 07, 2010 at 04:43:44PM -0700, H. Peter Anvin wrote:
>>> 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?
> 
> It's a pretty standard grub2 install (Debian unstable,
> 1.98~20100128-1.2) with something approaching the default config.  Grub
> does seem to put the console in some annoying framebuffer format to draw
> the boot menu, but IIRC it switches back to VGA textmode before booting
> the kernel.

Grub2 gratuitously bypasses the 16-bit initialization code in the Linux
kernel, that could easily be a source of bugs (and with Grub's track
record, probably is.)

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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