From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: [RFC] Reliable video POSTing on resume (was: Re: Samsung P35, S3, black screen (radeon)) Date: Thu, 10 Feb 2005 14:13:43 -0500 Message-ID: <420BB267.8060108@tmr.com> References: <20050205093550.GC1158@elf.ucw.cz> <1107695583.14847.167.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit In-Reply-To: <1107695583.14847.167.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@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: Alan Cox Cc: Pavel Machek , Jon Smirl , ncunningham-jjFNsPSvq+iXDw4h08c5KA@public.gmane.org, Carl-Daniel Hailfinger , ACPI List , Linux Kernel Mailing List List-Id: linux-acpi@vger.kernel.org Alan Cox wrote: > On Sad, 2005-02-05 at 09:35, Pavel Machek wrote: > >>Rumors say that notebooks no longer have video bios at C000h:0; rumors >>say that video BIOS on notebooks is simply integrated into main system >>BIOS. I personaly do not know if rumors are true, but PCs are ugly >>machines.... >> > > > A small number of laptop systems are known to pull this trick. There are > other problems too - the video bios boot may make other assumptions > about access to PCI space, configuration, interrupts, timers etc. > > Some systems (intel notably) appear to expect you to use the bios > save/restore video state not re-POST. Isn't that what it's there for? In any context other than save/restore I wouldn't think using the BIOS was a good approach. But this is a special case, and if there's a BIOS function which does the right thing, it would seem to be easier to assume that the BIOS works than that the driver can do every operation for a clean restart. The problem is that while POST leaves the video in a known state, it may not the known state you want, nor is it a given that you can get from there to where you were on suspend. PC hardware isn't always that dependable. -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979 ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click