How do I enable UDMA automatically

[Kalum Somaratna aka Grendel <kalum lintux cx>]

Greetings,

The kernel doesn't seem to use DMA, although i did indeed compile my
kernel with enable DMA access for the HDD set to on, it doesn't use it by
default...as seen with the hdparm program...
/sbin/hdparm /dev/hda

/dev/hda:
 multcount    =  0 (off)
 I/O support  =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  0 (off)
 keepsettings =  0 (off)
 nowerr       =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 1582/255/63, sectors = 25429824, start = 0

thses are the default settings, as you can see it is way inefficient,UDMA
is off, I/O support is 16 bit...and see the ratings for the test run with 

hdparm -t -T  /dev/hda

/dev/hda:
 Timing buffer-cache reads:   64 MB in  0.48 seconds =133.33 MB/sec
 Timing buffered disk reads:  32 MB in  7.38 seconds = 4.34 MB/sec

watch the buffered disk reads rating....

now I enable dma using -d1 and just see the difference

/sbin/hdparm -d1 /dev/hda

now I run the same test

/dev/hda:
 Timing buffer-cache reads:   64 MB in  0.43 seconds =148.84 MB/sec
 Timing buffered disk reads:  32 MB in  2.31 seconds =13.85 MB/sec

see when the dma is enabled it is 3 times faster!!!!

So what I want to ask is how to enable dma by default, should I put the
command in the inittab...???

Grendel

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