Re: [9fans] Enabling DMA causes newlines on console

[zfolkerts@mail.starcenter.tn.org]

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