Re: OT: getting up to udma 66 speed

[Alvin Oga <aoga@mail.Linux-Consulting.com>]

On Sun, 10 Apr 2005 gcrimp@vcn.bc.ca wrote:

> My abit vt6x4 motherboard "support[s] up to 4 udma 33/66 devices".  Without
> kernel boot arguments, it defaults to 33MHz bus speed.  I'm trying to figure
> out how to get this working (or maybe I already have:)

are we getting pci buss speed of 33Mhz and 66Mhz and 100Mhz confused
with ide disk drive buss speed of 33MB/sec, 66MB/sec, 100MB/sec vs
133MB/sec 

and we won't worry about whether the pci bus is 3.3v or 5v or ??

ide disk transfer speed is controlled by:

	hdparm -X 69 for ata-100  ( 100Mb/sec )
	hdparm -X 68 for ata-66 ( 66MB/sec )
	hdparm -X 67 for ata-33 ( 33MB/sec )

	almost nobody uses pio mode in favor of dma or udma for disks
	transfers

what is the output of:

	hdparm -iv /dev/hda ...

	- look for which udma mode is preceeded by a "*" to indicate its
	current disk transfer speed

more hdparm fun
	http://www.Linux-1U.net/Disks/hdparm.txt

you probably do not get to control via software, the PCI backplane speeds,
even more so, if you have a mixture of pci devices on the mb and the
plugin PCI cards

c ya
alvin