[LinuxBIOS] Winflashrom -- Current Status

Roman Kononov kononov at dls.net
Tue Aug 14 19:14:22 CEST 2007

On 08/14/2007 07:56 AM, Peter Stuge wrote:
> Roman did make a good point about IRQL but that does not eliminate
> the problem, we will still be changing hardware state underneath the
> OS and that is ALWAYS a bad idea.

The CF8/CFC sequence can preserve CF8 port value. What other hardware state 
  would be changed?

> http://www.hollistech.com/Resources/Misc%20articles/getbusdata.htm
> http://www.freelists.org/archives/wdmaudiodev/03-2004/msg00010.html

BTW, here is the "official" example:

Unfortunately, AFAIK, this approach does not work for cases like yours. It 
requires the "DeviceObject", which MUST be associated with a PARTICULAR PCI 

Q: In the above links, among HtsReadWriteConfig() and WritePCIConfigSpace() 
argument lists, which arguments are bus number and device number?
A: They are inside PDEVICE_OBJECT, which structure is "opaque".

Regarding how long DPC method takes. A scheduled DPC is launched as soon as 
the CPU's IRQL drops below DISPATCH_LEVEL. The CPU can be at DISPATCH_LEVEL 
(and higher) only running kernel code. This can last many time slices. This 
means that the DPC method might be quite expensive.



More information about the coreboot mailing list