Re: Calling PCI Autoconfig again

On Mar 7, 2006, at 10:53 AM, Mark Chambers wrote:

quoted

quoted

I'm dealing with this exact same situation and having a discussion  
on  lkml regarding the proper way to do this.  In your case, do  
you care  what addresses the FPGA is assigned at?
http://marc.theaimsgroup.com/?l=linux-kernel&m=114140791428032&w=2

Why does the PCI device have to have a fixed address?   And how do
you load an FPGA from user space - mmap?

In my case it does because we have other devices (DSPs) that are hard  
coded to know where in PCI address space the FPGA is.

Ah, ok.  So I'm guessing we're talking about DSP bus-master operations
where the DSP is putting out physical PCI space addresses that the
MMU can't help map.  I've run into a similar problem where I'd like to
be able to have a DSP do CPM/BD-like operations from SDRAM, but
it's exceedingly difficult to get the physical address of user-space data.

Well, FWIW, seems to me that something like what Greg K-H referred to,
where you pre-reserve space in PCI land, and then put the device there
when it becomes available, is the way to go.  Otherwise you have this
un-managed hole in PCI space allocation that might cause other problems 
with true hot-swap PCI, or break with kernel revisions.

Mark