hdd with dma disabled

[Emmanuel Pacaud]

Binary package hint: linux-source-2.6.20

Since the last update to 2.6.20, my hard disks have dma disabled.

I've tried to use hdparm -d 1 /dev/hda, but this command fails.

I've noticed a difference between 2.6.20 and 2.6.19: now hard disk are mounted as /dev/hdx, instead of /dev/sdx previously.

If I boot with the 2.6.19 kernel, dma is enabled.

[Gustavo Carneiro (gjc)]

I think I have the same problem. In 2.6.19 my PATA disk was seen as /dev/sda, now it's seen as /dev/hda (again). Also DMA is disabled.

I think DMA got disabled between 2.6.20-1-generic and2.6.20-2-generic; I'm pretty sure it was enabled a week or two ago with a 2.6.20 kernel.

My IDE controller is:

00:0f.1 IDE interface: VIA Technologies, Inc. VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 07)

[Gustavo Carneiro (gjc)]

OK, I went back and installed 2.6.20-1, and DMA is back and rocking with that kernel version. Definitely 2.6.20-2 broke it.

[Gustavo Carneiro (gjc)]

Never mind my last comment. It seems that either 2.6.20-1 or -2, or even 2.6.19 can either map IDE PATA disks as /dev/sd* or /dev/hd* depending on... *gasp* luck! If I keep rebooting the computer sometimes I get sda for my primary master IDE disk, sometimes I get hda. When I get hda, DMA is disabled (trasfer rate of 2.7 MB/s, and hdparm is unable to enable it); when I get sda, DMA is enabled (transfer rate of 61.7 MB/s).

PS: if the maintainers know of any kernel boot parameter to force sda I will appreciate it, at least as a temporary workaround... :P

[Martey Dodoo (martey)]

Is it possible that this bug is actually caused by initramfs-tools (see bug #76804)? Does downgrading that package solve the issue?

[Gustavo Carneiro (gjc)]

#76804 mentioned a workaround in #76872; I tried that and it works! I got DMA enabled in five consecutive boots, so it is probably fixed now.

So I guess you could mark both #76872 and #76911 as duplicates of #76804, to simplify tracking of bug; thanks!

[Launchpad Janitor (janitor)]

Beginning with the Hardy Heron 8.04 development cycle, all open Ubuntu kernel bugs need to be reported against the "linux" kernel package. We are automatically migrating this bug to the new "linux" package. However, development has already began for the upcoming Intrepid Ibex 8.10 release. It would be helpful if you could test the upcoming release and verify if this is still an issue - http://www.ubuntu.com/testing . If the issue still exists, please update this report by changing the Status of the "linux" task from "Incomplete" to "New". We appreciate your patience and understanding as we make this transition. Thanks!