UDMA Help! Intel 865G mobo.

deling · n00b Joined: 14 Jul 2003 Posts: 16

Hi all,

I can not seem to enable UDMA on my hard drive. I installed gentoo with the lastest version 1.4 (downloaded yesterday) with GRP. I did a "hdparm -t /dev/hda" and result is something like 3.xx MB/s. "hdparm -d /dev/hda" shows that UDMA is not enabled. "hdparm -d1 /dev/hda" simply failed saying "Operation not permitted" although I logged in with root.

I suspect this is a problem with the kernel. I tried to boot from a Knoppix Live CD and issued "hdparm -t" again, getting the same result. I downloaded 2.4.21 kernel source but it did not helped. In the configuration, I did not find the support for my IDE controller chip.

My mother board is an Intel 865G, IDE controller is supposed to be 82801. My harddriver is a seagate 80G, ATA100. I can get 80MB/s read speed on Windows XP, FreeBSD seems to have no problem either.

Anyone has any suggestion? Thanks a lot in advance.

irusun · n00b Joined: 11 Mar 2003 Posts: 27

I've had pretty much the exact same problem and have had a lot of difficulty finding answers (my theory is that there are a LOT of people who don't realize that they have not enabled DMA support). I'm not by any means an expert on this, but I do believe it's that your kernel lacks support for the ICH5. From the very little I've been able to track down, support for the ICH5 is available in the 2.6 test kernels as well as some of the recent Cox patches.

I tried compiling 2.6.0-test3 (search the gentoo forums on how to do that). For support of the Intel 865 (as well as most Intel chipsets), you'll want to include the Intel PIIXn chipset support in the ATA configuration section. After compiling the 2.6 kernel, I was able to enable DMA using the hdparm commands as you described.

Update: The new 2.4.22 kernel also supports the ICH5. Making the Intel PIIXn chipset support static (i.e. not as a module) worked for me.