Date: Tue, 11 Nov 2008 16:54:21 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Pavel Machek <pavel@suse.cz>
Cc: mathias.schnarrenberger@gmx.de, Olaf van der Spek <olafvdspek@gmail.com>,
       linux-kernel@vger.kernel.org
Subject: Re: security: delete BIOS password in keyboard buffer during kernel
 bootup
Message-ID: <20081111165421.4f1e836d@lxorguk.ukuu.org.uk>
In-Reply-To: <20081111161808.GA4473@ucw.cz>
References: <200811081100.03966.mathias.schnarrenberger@gmx.de>
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	<200811090941.20401.mathias.schnarrenberger@gmx.de>
	<20081109110814.13a4c099@lxorguk.ukuu.org.uk>
	<20081111161808.GA4473@ucw.cz>
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> OTOH we don't call BIOS from linux, so we assume that low 64K is
> usable memory (unless marked otherwise in memmap, I guess).

We use the BIOS in some cases for PCI routing, PCI services, APM, and
indirectly for SMM traps, ACPI and via user space for other stuff. So we
preserve the bottom 4K for the BIOS 0x40:xx page
> 
> Anyway, proper place to do clearing is bootloader; it interacts with
> bios already, anyway...

Agreed entirely.
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