[PATCH v6] numa: make node_to_cpumask_map() NUMA_NO_NODE aware

[Peter Zijlstra]

On Wed, Sep 25, 2019 at 11:45:26PM +0200, Peter Zijlstra wrote:
> [    7.149889] [Firmware Bug]: device: 'pci0000:7f': no node assigned on NUMA capable HW
> [    7.882888] [Firmware Bug]: device: 'pci0000:ff': no node assigned on NUMA capable HW

Going by the limited number of intel numa boxes I have, it looks like:

  socket = (~busid) >> (8-n)

where 'n' is the number of bits required to encode the largest socket
id, ie 1 for 2-socket and 2 for 4 socket.

For 8 socket systems we start using pci domains, and things get more
'interesting' :/