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From: Andrew Gallatin <gallatin@cs.duke.edu>
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Date: Tue, 30 Jan 2007 11:47:48 -0500 (EST)
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Subject: restoring PCI config space
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I need to write a watchdog handler for mxge(4).  The catch is that if
the NIC resets due to a hardware error, it will reset its config space
(setting BAR to 0, disabling DMA, forgetting MSI addr/data, etc), so
the driver's watchdog handler needs to be able to restore it.  How do
I do this properly on FreeBSD?

Browsing around the source tree, I see that the pci function
pci_cfg_restore() seems to do exactly what I want, but it is private
to the pci code, and seems to be called from the bowels of the resume
path.  Is there a clean way I can leverage pci_cfg_restore(), or
should I just save an extra copy of the device's PCI config space
myself?

Thanks,

Drew