[kvm-devel] [PATCH] [ACPI] Enable direct GSI mapping for APIC v2

[Alexander G. <ag...@su...>]

Hi,

in the DSDT there are two different ways of defining, how an interrupt
is supposed to be routed. Currently we are using the LNKA - LNKD method,
which afaict is for legacy support.
The other method is to directly tell the Operating System, which APIC
pin the device is attached to. We can get that information from the very
same entry, the LNKA to LNKD pseudo devices receive it.

For now this does not give any obvious improvement. It does leave room
for more advanced mappings, with several IOAPICs that can handle more
devices separately. This might help when we have a lot of devices, as
currently all devices sit on two interrupt lanes.

More importantly (for me) though, is that Darwin enables the APIC mode
unconditionally, so it won't easily run in legacy mode.

Regards,

Alex

Signed-off-by: Alexander Graf <ag...@su...>