From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <59b50c09ea943819b1eab81b3053c57f@plan9.bell-labs.com> From: jmk@plan9.bell-labs.com To: 9fans@cse.psu.edu Subject: Re: [9fans] Bug Report. Maybe DMA race on Abit BX6 In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Wed, 20 Aug 2003 15:01:08 -0400 Topicbox-Message-UUID: 1e3a79b8-eacc-11e9-9e20-41e7f4b1d025 On Wed Aug 20 14:53:28 EDT 2003, mirtchov@cpsc.ucalgary.ca wrote: > On Wed, 20 Aug 2003, Carl-Johan Kjellander wrote: > > > So there is a bug in the dma-handling for the Abit BX6 motherboard. > > > > according to jmk, if there was a bug in the dma code, data corruption > would be the most likely effect. however i've suffered only from race > conditions in fossil with dma on > > andrey The manifestation of DMA not being properly set up can range from subtle data corruption to system hangs. The problem is almost always caused by the BIOS setting the drive to a different DMA mode than that set in the controller-dependent registers. Plan 9 currently assumes the BIOS doesn't make that mistake, and that is why DMA should never be enabled unless you are sure it will work OK. The driver should someday be able to do this check and configure the hardware correctly.