Re: How do I debug PCI resource allocation problems

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To: Rainer Koenig <Rainer.Koenig@...>
Cc: <linux-kernel@...>
Date: Thursday, November 8, 2007 - 7:51 pm

Rainer Koenig wrote:

Looks like the BIOS reserved part of that memory range already. Question 
is why vesafb is trying to reserve that range in the first place though.


No, that's a virtual address.


64-bit capable PCI devices can indeed have BARs which can be located 
above 4GB. However, I can't see why lspci is detecting that from this 
configuration space: the BAR contents for region 2 are 20000008, which 
means prefetchable memory at 0x20000000 which can be located anywhere 
within 32-bit memory space. That doesn't make any sense though, since 
that's in the middle of RAM! Quite likely this bogus resource setting of 
the graphics controller is a large part of your problem. Question is 
who's doing this..


This looks more reasonable, though it's still mapped the BAR over top of 
a region that's reserved in the E820 memory map, which is wrong..


That looks more reasonable (e0000000, not 20000000). The last 4 bits are 
used to encode the prefetchable flag and memory space. Question is how 
that got set in the bogus fashion in Linux..



-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

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Messages in current thread:
Re: How do I debug PCI resource allocation problems, Robert Hancock, (Thu Nov 8, 7:51 pm)
Re: How do I debug PCI resource allocation problems, Rainer Koenig, (Fri Nov 16, 7:07 am)