topic Re: How do I enable IDE DMA ? in Operating System - Linux

How do I enable IDE DMA ?

Don Capps — Fri, 17 Dec 2004 12:21:34 GMT

Have ML110, Linux 2.4.20, Disk=Maxtor 80 Gbyte IDE, hdparm -t reports 5 Mbytes/sec (CRUD !)
hdparm -d1 fails with error. enable_dma=0
hdparm -X udma3/4/5 all fail with errors.
hdparm -X udma0/1/2 all work but enable_dma=0 and perf still 5 Mbytes/sec.
Suggestions please :-)

Re: How do I enable IDE DMA ?

Chris Xu — Fri, 17 Dec 2004 12:46:55 GMT

Try this:

# cd /proc/ide/hda/
# cat settings | grep using_dma

if you get 0 in first column, it means disabled and then try this:
# echo "using_dma:1" > /proc/ide/hda/settings

Re: How do I enable IDE DMA ?

Don Capps — Fri, 17 Dec 2004 12:56:34 GMT

Tried your suggestion.. No effect. Grep still says its off, and hdparm -d /dev/hda also indicates that it is still off.

Any other ideas ?

Re: How do I enable IDE DMA ?

Chris Xu — Fri, 17 Dec 2004 13:01:12 GMT

You probably need to upgrade your kernel to at lease 2.4.21. Here is a link to a posting related to dma - https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=103923

Not exactly same problem as yours, but enough indications for an upgrade in need. I have systems with 2.4.21 and I can easily turn dma on or off.

Re: How do I enable IDE DMA ?

Don Capps — Fri, 17 Dec 2004 13:19:43 GMT

That's cool, but it no effect. The reason that has no effect is because the patch is to lines inside of an #ifdef that in my case is not true.

#CONFIG_IDEDMA_ONLYDISK is not set

Also noteworthy, is that I have other systems with the same kernel and DMA works fine. It's something about the Proliant ML110 that is disabling the DMA.

Next idea ?

Re: How do I enable IDE DMA ?

Don Capps — Fri, 17 Dec 2004 13:42:19 GMT

Perhaps more details will help. It looks like the Proliant ML110 has an IDE device that is not well understood by 2.4.20 ? Is this whats disabling DMA ? If so, any suggestions ?

The output from lspci -v

00:1f.1 IDE interface: Intel Corp.: Unknown device 25a2 (rev 02) (prog-if 8a [Ma
ster SecP PriP])
Subsystem: Hewlett-Packard Company: Unknown device 0000
Flags: bus master, medium devsel, latency 0
I/O ports at
I/O ports at
I/O ports at
I/O ports at
I/O ports at 1460 [size=16]
Memory at 10000000 (32-bit, non-prefetchable) [disabled] [size=1K]

Re: How do I enable IDE DMA ?

xyko_1 — Fri, 17 Dec 2004 13:43:01 GMT

Hi Don,

Is it possible that dma is disabled on bios ?

regards,
Xyko

Re: How do I enable IDE DMA ?

Don Capps — Fri, 17 Dec 2004 14:02:04 GMT

I believe that it has something to do with the fact that the the IDE device is an Intel Corp 0x25a2 device and that it is not listed in linux/drivers/pci/devlist.h So... the kernel doesn't know what capabilities this IDE chipset has, so it's unable to turn on DMA. Any chance there is a patch to 2.4 that addes on the newer Intel IDE chipsets ?

Re: How do I enable IDE DMA ?

Chris Xu — Fri, 17 Dec 2004 14:17:07 GMT

I think you are on the right track. BTW, did you take a look at /usr/src/linux-2.4/Documentation/ide.txt?

Re: How do I enable IDE DMA ?

Don Capps — Fri, 17 Dec 2004 16:37:52 GMT

I think I'm getting closer...
It appears that it may be possible to patch the 2.4 kernel with some code from Intel and then get the DMA working.
To be kind, here is the link:
http://downloadfinder.intel.com/scripts-df/Detail_Desc.asp?agr=Y&ProductID=1706&DwnldID=7741

Re: How do I enable IDE DMA ?

Johannes Krackowizer_1 — Mon, 20 Dec 2004 04:25:17 GMT

hi Don Capps,

did you look at your bios settings? perhaps dma is disabled in bios and the linux kernel could not work around the bios because of a buggy bios. try to enable it in bios.

best regards,

johannes