Re: Calibration issues with USB disc present.

[George Anzinger <george@mvista.com>]

john stultz wrote:
> On Mon, 2005-11-14 at 10:49 -0800, Greg KH wrote:
> 
>>On Mon, Nov 14, 2005 at 10:56:05AM -0800, George Anzinger wrote:
>>
>>>Greg KH wrote:
>>>
>>>>On Sat, Nov 12, 2005 at 08:06:37AM -0800, George Anzinger wrote:
>>>>
>>>>>Greg KH wrote:
>>>>
>>>>On these boxes, I'd just recommend disabling USB legacy support
>>>>completly, if possible.  And then complain loudly to the vendor to fix
>>>>their BIOS.
>>>
>>>But if one is booting from that device...
>>
>>Booting from a USB device?  I can see this happening when installing a
>>distro, and you boot from the USB cdrom, but not for "normal"
>>operations.

I think it was a hard drive they were trying to support.
>>
>>Oh well, publicly mock the manufacturer for doing horrible things in
>>their BIOS and then no one will buy the boxes, and we will not have
>>problems :)

Long term, maybe, but it will not close the bug report I have in hand...
> 
> 
> I suspect the right fix is in-between. We should try to push hardware
> makers away from using SMIs recklessly, but we should also do our best
> to work around those that don't. The same problems crop up w/
> virtualization where time-based calibration may be interrupted.
> 
> George, again, there has been some SMI resistant delay calibration code
> added recently. You mentioned this problem was seen on 2.4 kernel, so
> you could verify that the new code in 2.6.14 works and if so, try
> backporting it.
> 
> If not we need to see what else we can do about improving delay
> calibration (its a similar tick-based problem to what I'm addressing
> with the timeofday rework) or reducing the use of delay by using
> something else.
> 
I will look at that code, but we also need to address the same problem in the TSC calibration area.
-- 
George Anzinger   george@mvista.com
HRT (High-res-timers):  http://sourceforge.net/projects/high-res-timers/