[techtalk] hdparm and DMA "not permitted"

Penguina penguina at cosyn.co.nz
Wed May 23 11:36:23 EST 2001


WOW THANKS!

I just recompiled my 2.4.0 kernel with generic dma support
for the IDE driver on my laptop, and it more than quadrupled my
disk reads.  (We'll see how it handles disk *writes* from my DV
camera now...)

more explicit directions:

If you're using "make xconfig" go to the button labelled
"ATA/IDE/MFM/RLL support" and in that dialog box you should
see "IDE, ATA and ATAPI Block devices" -- click that, and
it takes you to yet another dialog box.  Scroll down down
down to "Generic PCI bus-master DMA support" and click "y"

If you're editing your .config by hand, it's

CONFIG_BLK_DEV_IDEDMA_PCI=y

and if you're using "make config" god help you.
I mean, answer "yes" when it asks about
"Generic PCI bus master DMA support".

Then it's the usual "make bzImage", editing lilo.conf,
re-running lilo and placing bzImage in your /boot dir.

fun fun fun!!!

Thanks again!

Cheryl

Conor Daly:
> > > [root]# /sbin/hdparm -d 1 /dev/hda
> > >
> > > /dev/hda:
> > >  setting using_dma to 1 (on)
> > >  HDIO_SET_DMA failed: Operation not permitted
> > >  using_dma    =  0 (off)
> > >
> > > dmesg returns:
> > >
> > > PCI_IDE: unknown IDE controller on PCI bus 00 device 78, VID=10b9,
> > > DID=5229
> > > PCI_IDE: not 100% native mode: will probe irqs later
> > > PCI_IDE: simplex device:  DMA disabled
> > > hda: Maxtor 91021U2, 9770MB w/512kB Cache, CHS=1245/255/63
> > > hdb: FUJITSU MPD3084AT, 8063MB w/512kB Cache, CHS=1027/255/63
> > >
> > > Any thoughts?
> >
> > Enabling DMA requires the right driver in the kernel; there is an
option
> > for "Generic PCI DMA support" or similar, which might be worth a try
if
> > you can't find an exact match for your IDE chipset.
> >





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