Re: Problems w/ UDMA

Roy P. Turner (
Wed, 25 Feb 1998 17:30:29 -0600

In message <>, Steven Suson writes:
> We are currently trying to boot (a highly modified) RH4.2 w/ 2.1.78
> kernel. If we either turn on UDMA in the BIOS and enter ide0=noautotune,
> or turn off UDMA in the BIOS it boots, using PIO. Otherwise it hangs at
> the point that it accesses the drive, with the disk access light on
> solid. Any assistance would be greatly appreciated.

I notice you're using Western Digital drives on a VIA chipset. I also use
Western Digital UDMA drives on a VIA chipset based board (FIC PA-2007 w/
VIA VP2 chipset) and I do have problems with the drives in UDMA mode *IF*
I turn on write cacheing with hdparm. The drives work fine in UDMA mode
with write cacheing off and they work fine in non UDMA mode with write
cacheing both on and off. I'm pretty sure it's a kernel problem as the
drives work fine in UDMA mode with write cacheing on under winblowz.
My question to you is if your're turning write cacheing on early in you
boot sequence or does your bios have the ability to set write cacheing
on or off. My drives are WD AC22000L and WD AC121000L.

Thanks, Roy

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