Re: CVS commit: src/sys/dev/pci

["Jonathan A. Kollasch" <jakllsch%kollasch.net@localhost>]

On Wed, May 16, 2018 at 12:50:22PM -0700, Jason Thorpe wrote:
> 
> 
> > On May 16, 2018, at 12:02 PM, Jonathan A. Kollasch <jakllsch%netbsd.org@localhost> wrote:
> > 
> > Module Name:	src
> > Committed By:	jakllsch
> > Date:		Wed May 16 19:02:00 UTC 2018
> > 
> > Modified Files:
> > 	src/sys/dev/pci: pci_map.c
> > 
> > Log Message:
> > Enable the appropriate memory or I/O space decode in the PCI
> > Command/Status Register upon mapping a BAR.
> > 
> > This should fix PR #53286.  It's also possible there are other similar
> > PRs that might be fixed by this.
> 
> This change makes me a tad uneasy, mainly because it doesn’t seem to ensure that that the BAR contains something sensible before enabling the decode.

I'm a bit uneasy about it myself for that same reason.  However, we
do not to my knowledge have the infrastructure available to do a
complete validation of the resource assignment.  If we did, we'd be
able to do hot attach of PCIe ExpressCard with just a little more work.

The worst case scenario is that we deface essential non-volatile memory
somewhere.  However, the more likely failure scenario is that some
bit of memory or MMIO starts getting decoded by the wrong device and
the machine does something between triple fault and hardware deadlock.

	Jonathan Kollasch