Hi Gentoo Kernel folks ;-)
I was wondering if you could push this patch upward in the kernel tree. It's for DMA on the ICH6_5 chipset from intel, which is found on some laptops. I'm using a Eurocom M560A.
I have been manually applying this patch since about March 2006 from kernels upward of 2.6.16. The problem was that I got this (garbage) laptop from work, immediately loaded gentoo on it, and noticed that everything from disk reads, to running X, or reading a CDROM was dreadfully slow - DMA of course ;-)
Then I did some research on the mainboard to see if there was something missing, tried running Ubuntu, and noticed that it lacked the slowness described above. I found this URL with a fairly anonymous patch and I guess up until now it hasn't sneaked into the kernel.
This patch is extremely basic, and only adds a couple of new definitions which are supported by the existing kernel code. very harmless, but it increased my disk throughput by something like 3000% :)
Steps to Reproduce:
1.you will need a laptop with ICH6_5 / 82801FB (Mobile chipset) from intel.
2. use any gentoo kernel as is
3. hdparm -tT <your root device>
something like 3MB/sec
Check out the original patch at
It has a bit more context which could be helpful.
I think this is deliberately excluded because it supports the newer AHCI modes so you do not need to run it in blk_dev_piix legacy mode.
Try the ATA_PIIX driver. Note that your disk will move from hda to sda.
see comment #1
I just tested it out - what was wierd was that with the old ATA_PIIX driver, the disks would still show up as /dev/hdc ...
After changing to the newer driver, they are now /dev/sda ...
It's working very well now
Thanks for the help ;-)