linux-kernel - Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

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Date:	Tue, 08 May 2007 19:23:03 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	yhlu <yhlu.kernel@...il.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>, vgoyal@...ibm.com,
	Gerd Hoffmann <kraxel@...hat.com>,
	Jeff Garzik <jeff@...zik.org>, patches@...-64.org,
	linux-kernel@...r.kernel.org,
	virtualization <virtualization@...ts.linux-foundation.org>,
	Rusty Russell <rusty@...tcorp.com.au>, Andi Kleen <ak@...e.de>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for
 relocatable bzImage

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
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