Please excuse if this is a stupid question - my i386 knowledge is limited
and I know nothing about ACPI.

I have a problem though, and the full story is recorded in PR 33922.

On my notebook the ath0 wlan and the auich0 sound device share an
interrupt, and both point to an acpi link dev that ends up in 
NetBSD as:

 Link Device LNKB:
 Index  IRQ  Rtd  Ref  IRQs
     0  255   N     5  5 7


The offerered IRQs (5 and 7) would be fine AFAICT (windows uses 5), but
NetBSD rejects them, because they are not in the pci_link_bios_isa_irqs
bitmask. (The code is in sys/dev/acpi/acpi_pci_link.c, function
acpi_pci_link_choose_irq.)

Can anyone explain the reasoning for this additional test and why we don't
trust ACPI to tell us the truth? Maybe we should have at least a kernel
option to do so (simplest implementation: just initialize the bitmask to
all 1s, but I'm not sure there would be some other IRQ initialization
needed in this case).

Martin