Re: ASUS KT266A/VT8233 board and UDMA setting

From: Dmitri Pogosyan (
Date: Sat Jan 05 2002 - 14:20:40 EST

Alan Cox wrote:

> > Some RH kernels (may include yours) deliberately disable UDMA3, 4 and 5
> > on any VIA IDE controller. I don't know why. Unpatch your kernel and
> > it'll likely work.
> RH 2.4.2-x. That was before we had the official VIA solution to the chipset
> bug. It was better to be safe than sorry for an end user distro.

Yes, indeed. Seems RH-2.4.16-0.13 kernel still enforces disabling UDMA>2 for
by means of setting cable type to 40w, even if 80w is present

#cat /proc/ide/via

------------ ---Primary IDE-----Secondary IDE------
Read DMA FIFO flush: yes yes
End Sector FIFO flush: no no
Prefetch Buffer: yes no
Post Write Buffer: yes no
Enabled: yes yes
Simplex only: no no
Cable Type: 40w 40w

If I force higher UDMA by ide0=ata66 kernel option, as discussed in RH bug
ide0 zero is set to UDMA5 (not the cable though) and everything is working.

I'll file a bug against RH kernel.

                Thanks everybody, Dmitri

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