Non aligned DMA transfer errors with k3b
jmc-freebsd at milibyte.co.uk
Sun May 25 20:22:44 UTC 2008
Suddenly today all my attempts to burn DVDs with k3b result in a
continuous stream of the following error messages.
May 25 18:04:40 kestrel kernel: ata1: FAILURE - non aligned DMA transfer
May 25 18:04:40 kestrel kernel: acd0: setting up DMA failed
Quiting k3b doesn't stop the flood of errors, reboots hang and the only
solution is to hit the reset switch.
I'm running 7.0 RELEASE and if I reboot into my 6.3 partition k3b works
just fine, confirming that it's not a media or hardware fault. I've
also replaced the DVD writer but I still get the problem with 7.0.
I can burn the same data to the same DVD with growisofs with no problem
which suggests that the problem lies with k3b so this got me wondering
if it was related to the massive portupgrade I did yesterday (affecting
156 ports) but that seems unlikely because when portupgrade finished
last night I rebooted and burnt that day's backup to DVD+RW without
problem. This morning I burnt 3 DVD+Rs without problem, then about an
hour later the problem suddenly appeared when I started to burn another
DVD+RW, and there'd been absolutely no software or hardware changes
since the previous successful run.
Although I don't think upgrading the ports is responsible I've tried
downgrading k3b from 1.0.4_1 to 1.0.4 but that had no effect, nor did
downgrading dvd+rw-tools-7.1 to 7.0. I don't think any of the other
upgraded ports would have been significant.
Turning off DMA by setting hw.ata.ata_dma and hw.ata.atapi_dma to zero
stops the errors but with a big performance hit so that's not an option
for a permanent fix.
I've now run out of ideas for what to try next so any suggestions would
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