linux-kernel - Re: [PATCH v5] x86: Enable fast strings on Intel if BIOS hasn't already

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Message-ID: <m21u9qve23.fsf@firstfloor.org>
Date:	Wed, 01 May 2013 09:51:32 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	Theodore Ts'o <tytso@....edu>
Cc:	Borislav Petkov <bp@...en8.de>,
	Andy Lutomirski <luto@...capital.net>,
	linux-kernel@...r.kernel.org, x86@...nel.org,
	Andrew Lutomirski <luto@....edu>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v5] x86: Enable fast strings on Intel if BIOS hasn't already

Theodore Ts'o <tytso@....edu> writes:
>
> In fact, there is the question of whether we should be checking to see
> if the CPU stepping is one of the ones with the bug, and if so, to
> have Linux disable fast strings even if the BIOS didn't, instead of
> blindly enabling fast strings....

Crossing pages with different memory attributes shouldn't happen 
in normal operation. I wouldn't be too concerned about that one.

I would suggest to leave the bit alone. There may be valid
reasons on the system to either set or not set it, which the kernel
doesn't necessarily know.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only
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