On Wed, Aug 17, 2005 at 01:06:30PM -0500, Ardo van Rangelrooij wrote: > I ran into an interesting DMA issue in 2.6.12 vs. 2.6.11: > > First some info on the system I'm running the latest and greatest sid on: > > Asus A8V Deluxe > AMD Athlon64 3000+ > 1G dual channel DDR (2x512MB) > /dev/sda = Maxtor 6B200M0 > /dev/hda = Sony DVD-ROM DDU1622 > /dev/hdb = WDC WD1200JB-75CRA0 > /dev/hdc = Maxtor 6B200R0 > /dev/hdd = WDC WD1200JB-00EVA0 > > /dev/sda has / and swap > /dev/hdb and /dev/hdd are in /dev/md0 as raid-1 > > When using 2.6.11-9 everything is ok and as expected: The DMA flags are set > when running `cat /proc/ide/hd[bcd]/settings`, running `hdparm -T` gives > 1800+ MB/sec, and running `hdparm -t` gives 45MB/sec for /dev/md0 and 54MB/sec > for /dev/hdc. So far so good. > > However, when running 2.6.12-1 things are not as expected: The DMA flags are > not set, and running hdparm I get much lower numbers. And I get > > > hdparm -d 1 /dev/hdc > > /dev/hdc: > setting using_dma to 1 (on) > HDIO_SET_DMA failed: Operation not permitted > using_dma = 0 (off) > > When booting nothing in the log files indicates something's wrong or > whatever. > > Anybody any thoughts?
Somehow the new kernel is loading ide-generic first and it takes control of the ide interfaces and of course doesn't allow dma at all since that is a chipset specific feature. lsmod should show which driver has how many uses of it. dmesg should also show which driver grabbed each device. the initrd tools has loaded ide-generic too early in the past, as has some driver dependancy bugs once upon a time too. Len Sorensen -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
