[vfio-users] Bus reset trouble with Titan-X (was Re: Welcome to the "vfio-users" mailing list (Digest mode))

[Alex Williamson]

(generally a good idea to have a useful subject line)

On Mon, 17 Oct 2016 16:26:15 -0500
Kevin Vasko <kvasko at gmail.com> wrote:
> 
> Any suggestions on debugging a !!! Unknown header type 7f?
> 

This usually means that the device didn't come back from bus reset and
re-reading the PCI config space where the device was just gives a -1
response.  lspci tries to interpret that bogus data and gives results
like you see.  You might try a newer kernel, we've probably fixed some
things in the bus reset path since v3.19.  It looks like you continue
to see the bogus data once it gets into this state, so it's probably
not a "simple" device coming out of reset too slowly problem.  Possibly
the PCIe link doesn't retrain properly sometimes after a bus reset.  If
a new kernel doesn't help, I could give you instructions for performing
a bus reset with setpci and you could test how reliably you can reset
the device and read config space after.  Thanks,

Alex