From mboxrd@z Thu Jan 1 00:00:00 1970 From: zfolkerts@mail.starcenter.tn.org To: 9fans@cse.psu.edu Subject: Re: [9fans] Enabling DMA causes newlines on console Message-ID: <20030714172823.GA13597@antares> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.4i Date: Mon, 14 Jul 2003 12:28:23 -0500 Topicbox-Message-UUID: f865961e-eacb-11e9-9e20-41e7f4b1d025 On Mon, Jul 14, 2003 at 10:50:38AM -0400, jmk@plan9.bell-labs.com wrote: > On Mon, 14 Jul 2003 zfolkerts@starcenter.tn.org wrote: > > If I enable DMA on my disks I get blank lines on the console whenever > > I do disk I/O. Basically this prevents me from using rio while any > > I/O is happening. I think there may be a blank message echoed to the > > console in the IDE driver or somewhere. This does not happen if I do > > not have DMA enabled. This seems to happen even if I only enable DMA on > > do a simple test - bring the system up to a shell prompt (i.e. no window > manager) - enable dma then dd from one of discs to /dev/null, see what happens. Well, I rebooted the box, and found that there was no longer a partition table on either of the drives attached to the Promise controller(lc /dev/sd[EF]0 only gives ctl data and raw). Other than that, these were the results: with dma on: /dev/sdC0 no newlines to console /dev/sd[EF]0 newlines to console with dma off: /dev/sdC0 newlines to console /dev/sd[EF]0 newlines to console Could enabling dma on the Promise controller have trashed the partition table? (I seem to remember a message to 9fans saying some controllers trash data with dma enabled) Also which controllers are recommended? I also have a Promise Ultra 66, and a CMD 640b(I haven't tried to use this under Plan 9 since it is so old). Luckily I have my fossil on the first drive in the system, so I don't have to recreate that, however I am curious whether I should just get rid of the offboard controller entirly making one of the drives slave to another. I had originally put the Ultra 100 in so I could keep all of my disks as masters. Any suggestions are appreciated. Thanks, Zack Folkerts