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Date: Tue, 08 May 2007 19:23:03 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: "Eric W. Biederman" <ebiederm@xmission.com>
CC: yhlu <yhlu.kernel@gmail.com>, Jeremy Fitzhardinge <jeremy@goop.org>,
       vgoyal@in.ibm.com, Gerd Hoffmann <kraxel@redhat.com>,
       Jeff Garzik <jeff@garzik.org>, patches@x86-64.org,
       linux-kernel@vger.kernel.org,
       virtualization <virtualization@lists.linux-foundation.org>,
       Rusty Russell <rusty@rustcorp.com.au>, Andi Kleen <ak@suse.de>,
       Ingo Molnar <mingo@elte.hu>
Subject: Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for
 relocatable bzImage
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Eric W. Biederman wrote:
> 
> I expect I can find a few more examples where we specify
> video_cols and video_lines but we use video_mode == 0.
> 
> Going farther mode 0x00 is a BIOS 40x25 mode.  So the patch below is
> not always safe even if we boot the bzImage.  It is just highly
> unlikely anyone would start the kernel in 40x25 text mode. 
> 

Mode 0x00 is, at least theoretically, BIOS 40x25 *grayscale*; this mode
(and mode 0x02 which is the same thing in 80x25) were as far as I know
only ever used with composite monitors off CGA cards, i.e. functionally
never.  Actual monochrome monitors used mode 0x07.

	-hpa