At 02:32 10/03/2005 +0000, Todd Walton wrote: >I'm having trouble with DMA on my disks. I've used DMA on these IDE >disks before, but for some reason I can't now. When I run "hdparm >-X66 -d1 -u1 -m16 -c3 /dev/hda", for example, it all sets fine except >DMA. For that it says, "HDIO_SET_DMA failed: Operation not >permitted". I know I've used DMA on these two drives before. I >checked my kernel config and, sure enough, I have DMA enabled: > >linux # zcat /proc/config.gz |grep DMA >CONFIG_GENERIC_ISA_DMA=y >CONFIG_ISA_DMA_API=y >CONFIG_BLK_DEV_IDEDMA_PCI=y ># CONFIG_BLK_DEV_IDEDMA_FORCED is not set >CONFIG_IDEDMA_PCI_AUTO=y ># CONFIG_IDEDMA_ONLYDISK is not set >CONFIG_BLK_DEV_IDEDMA=y ># CONFIG_IDEDMA_IVB is not set >CONFIG_IDEDMA_AUTO=y > >What else can I check?
What makes you think that DMA isn't working? Normally you don't have to do anything to get the maximum performance settings from your hard drives; when the system boots the kernel just "knows" what to do. Try running hdparm -i /dev/hda and look at the DMA settings. If there is an asterisk next to the [U]DMA setting, then the drive is running in [U]DMA mode. If the drive isn't being picked up in DMA mode then you might have some other problem. Try booting the system with Knoppix and see what it shows. Maybe the reason you can't set the DMA mode is because the drive is already mounted and in use. See what happens if you set DMA on in Knoppix. Gus -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
