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From: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
To: Dave Jones <davej@codemonkey.org.uk>,
	David Brownell <david-b@pacbell.net>,
	Jeff Garzik <jgarzik@pobox.com>, Greg KH <greg@kroah.com>,
	Russell King <rmk@arm.linux.org.uk>,
	Linus Torvalds <torvalds@transmeta.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [patch 2.5] PCI MWI cacheline size fix
Date: Thu, 20 Mar 2003 15:29:56 +0300	[thread overview]
Message-ID: <20030320152956.A2584@jurassic.park.msu.ru> (raw)
In-Reply-To: <20030320115520.GB6995@suse.de>; from davej@codemonkey.org.uk on Thu, Mar 20, 2003 at 11:55:20AM +0000

On Thu, Mar 20, 2003 at 11:55:20AM +0000, Dave Jones wrote:
>  > +	else if (c->x86 > 6)
>  > +		pci_cache_line_size = 128 >> 2;	/* P4 */
>  >  
> 
> I'd feel more comfortable with this with a c->x86_vendor == X86_VENDOR_INTEL
> on the else if clause. The above code will silently break if for eg,
> VIA, Transmeta or any other clone manufacturer make a model 7 or higher CPU.

No, we'd just assume 128 bytes cache line size on such CPU, which is
safe unless it has cache lines larger than 128. But if we assume 32 bytes
while this new CPU has 64, MWI might corrupt memory by transferring
incomplete cache lines.

Ivan.

  reply	other threads:[~2003-03-20 12:19 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-03-20 10:59 Ivan Kokshaysky
2003-03-20 11:55 ` Dave Jones
2003-03-20 12:29   ` Ivan Kokshaysky [this message]
2003-03-20 12:54     ` Dave Jones
2003-03-20 14:33 ` Jeff Garzik
2003-03-20 15:29 ` David Brownell
2003-03-20 22:26 ` Greg KH

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