DMA issues

[Jason Bradley Nance]

I'm either having trouble enabling DMA on my system, or determining that 
DMA is enabled (for both a SATA hard disc and two optical devices).

For my SATA hard drive (ICH6), how can I determine if DMA is enabled?  I 
checked the BIOS, and it says that the UDMA mode is 5.

For my optical drives - one DVD-ROM and one DVD burner (both PATA) - I 
see the following:

$ sudo hdparm -v /dev/hda

/dev/hda:
  HDIO_GET_MULTCOUNT failed: Invalid argument
  IO_support   =  0 (default 16-bit)
  unmaskirq    =  0 (off)
  using_dma    =  0 (off)
  keepsettings =  0 (off)
  readonly     =  0 (off)
  readahead    = 256 (on)
  HDIO_GETGEO failed: Invalid argument

This is for the DVD-ROM (it's /dev/hda because there are no PATA hard 
drives in the system).

When I attempt to change the DMA settings, I get this:

$ sudo hdparm -c 1 -d 1 -a 8 -u 1 /dev/hdb

/dev/hdb:
  setting fs readahead to 8
  setting 32-bit IO_support flag to 1
  setting unmaskirq to 1 (on)
  setting using_dma to 1 (on)
  HDIO_SET_DMA failed: Operation not permitted
  IO_support   =  1 (32-bit)
  unmaskirq    =  1 (on)
  using_dma    =  0 (off)
  readahead    =  8 (on)

DMA remains off.

However, /proc/ide/piix says:

Controller: 0

                                 Intel PIIX4 Ultra 100 Chipset.
--------------- Primary Channel ---------------- Secondary Channel 
-------------                 enabled                          enabled
--------------- drive0 --------- drive1 -------- drive0 ---------- 
drive1 ------DMA enabled:    yes              yes             no 
         no
UDMA enabled:   yes              yes             no                no
UDMA enabled:   2                2               X                 X
UDMA
DMA
PIO

(there's only 1 IDE channel on the motherboard)

I checked in the BIOS and both optical devices are set at UDMA mode 2.

I've tried unloading the sr_mod module.  I've also tried loading the 
ide-cd module with "dma=1".

I don't think that DMA is enabled because when I play DVDs the system is 
sluggish even though the load average is practically 0.  This box is a 
P4 3.2 GHz HT box with 1 GiB of DDR2 RAM and a PCX nVidia 5900, so it 
should be able to play DVDs without any problem.

Any insight on this would be much appreciated.

j


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Jason Bradley Nance                        What would you cry for?
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