Panic on boot with today's CURRENT, ata related

[Nate Lawson]

Radek Kozlowski wrote:
> On Fri, Aug 06, 2004 at 03:31:06PM -0700, Nate Lawson wrote:
> 
>>It looks like the DMA object for the channel is not being initialized. 
>>However, that is in another path (this backtrace is just a symptom 
>>triggered by the first DMA access to the drive).  Someone who knows more 
>>about the control path for going from PIO -> DMA mode will have to look 
>>into this.
> 
> I would like to stress that it only happens with ACPI enabled. If I boot
> with ACPI disabled the transfer mode is set to UDMA100. Shall I provide
> you with more info?

I'm done debugging ATA for now.  I spent 8 hours tracking down the first 
bug (not counting the time lost tracking down a non-existent routing 
table bug triggered by the ATA bug) and 15 minutes on the second one.

ACPI does not affect ATA other than setting up IO ports and IRQs.  I 
have no idea what can cause ATA to use PIO over UDMA.

-- 
Nate