linux-kernel - Re: [x86] only print out DR registers if they are not power-on defaults.

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Message-ID: <20130619215233.GU28300@pd.tnic>
Date:	Wed, 19 Jun 2013 23:52:34 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>, x86@...nel.org
Subject: Re: [x86] only print out DR registers if they are not power-on
 defaults.

On Wed, Jun 19, 2013 at 02:42:49PM -0700, H. Peter Anvin wrote:
> There is serious confusion with regards to DR6 about the bits which
> are *fixed* (forced to 1) and the ones which are *reserved* (should
> always have a fixed value.)
>
> There are some bits in DR6 which are used by hardware probes.

Haha, I knew it! HW guys don't care about the architectural documents.

Maybe DR6 should probably be dropped altogether from the check before
exiting __show_regs early?

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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