From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phillip Susi Subject: Re: Information regarding C3 cpu state and bus mastering activity Date: Sun, 11 Dec 2005 22:42:15 -0500 Message-ID: <439CF197.3090902@cfl.rr.com> References: <439CC549.5060500@tzi.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <439CC549.5060500-cGBD8117FJM@public.gmane.org> Sender: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-acpi@vger.kernel.org I'm kind of confused as to why this is a problem myself. Yes, the CPU cache does not snoop the busmaster activity and so the cache can become out of sync with ram, but isn't it the job of the driver that initiates the dma transfer to invalidate those cache lines once the transfer is complete to bring the cache back into sync? Janosch Machowinski wrote: > > No this is not Possibe. In C3 the processor disables his cache. If you > have busmaster activity, there are direct writes into the cache (if I > remeber right). So if you allow C3 and Busmaster, you will get into some > serious truble and loose data. > ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click