[...]
I believe assign_irq_vector on x86_64 and soon on x86_32 does this already.
The number that was being changed was the irq number of for the
msi-x ``vectors'' from some random free irq number to roughly
bus(8 bits):device+function(8 bits):msix-vector(12 bits) so that we
could have a stable irq number for msi irqs.
Once pci domain is considered it is hard to claim we have enough bits.
I expect we need at least pci domains to have one per NUMA node, in
the general case.
So once we have all of that. It becomes possible to look at assigning a static
irq number to each pci (bus:device:function:msi-x vector) pair so the system
is more reproducible.