This one would be nice to go to stable, but I'm not sure it really meets
the rules. It could be a problem for userspace error paths checking the
result of MMIO reads, but only if the AFU has actually been unexpectedly
disabled somehow yet the PSL is still responding...
I don't think this is a high
From: Ian Munsie
Upon inspection of the implementation specific registers, it was
discovered that the high bit of the implementation specific RXCTL
register was enabled, which enables the DEADB00F debug feature.
The debug feature causes MMIO reads to a disabled AFU to respond with
0xDEADB00F ins
