such that nfe(4) does not work with MSI-X. When MSI-X support was
introduced, I remember MCP55 controller worked without problems so
the issue could be either PCI bridge or BIOS issue. But I also
noticed snd_hda(4) disabled MSI on all MCP55 chipset so I'm still
not sure this is generic issue of MCP55 chipset. If this was PCI
bridge issue we would have added it to a system wide black-list
table but it's not clear to me at this moment whether it was caused
by either broken BIOS or silicon bug of MCP55 chipset.
To workaround the issue, maintain a MSI/MSI-X black-list table in
driver and lookup base board manufacturer and product name from the
table before attempting to use MSI-X. If driver find an matching
entry, nfe(4) will not use MSI/MSI-X and fall back on traditional
INTx mode. This approach should be the last resort since it relies
on smbios and if another instance of MSI/MSI-X breakage is reported
with different maker/product, we may have to get the PCI bridge
black-listed instead of adding an new entry.
PR: kern/152150
7e7a45ce6f