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On a real system with POWER{8,9,10} processors, PHBs are sub-units of
the processor, they can be deactivated by firmware but not plugged in
or out like a PCI adapter on a slot. Nevertheless, having user-created
PHBs in QEMU seemed to be a good idea for testing purposes :
1. having a limited set of PHBs speedups boot time.
2. it is useful to be able to mimic a partially broken topology you
some time have to deal with during bring-up.
PowerNV is also used for distro install tests and having libvirt
support eases these tasks. libvirt prefers to run the machine with
-nodefaults to be sure not to drag unexpected devices which would need
to be defined in the domain file without being specified on the QEMU
command line. For this reason :
3. -nodefaults should not include default PHBs
User-created PHB{3,4,5} devices satisfied all these needs but reality
proves to be a bit more complex, internally when modeling such
devices, and externally when dealing with the user interface.
Req 1. and 2. can be simply addressed differently with a machine option:
"phb-mask=<uint>", which QEMU would use to enable/disable PHB device
nodes when creating the device tree.
For Req 3., we need to make sure we are taking the right approach. It
seems that we should expose a new type of user-created PHB device, a
generic virtualized one, that libvirt would use and not one depending
on the processor revision. This needs more thinking.
For now, remove user-created PHB{3,4,5} devices. All the cleanups we
did are not lost and they will be useful for the next steps.
Fixes:
|
||
|---|---|---|
| .. | ||
| authz | ||
| block | ||
| chardev | ||
| crypto | ||
| disas | ||
| exec | ||
| fpu | ||
| hw | ||
| io | ||
| libdecnumber | ||
| migration | ||
| monitor | ||
| net | ||
| qapi | ||
| qemu | ||
| qom | ||
| scsi | ||
| semihosting | ||
| standard-headers | ||
| sysemu | ||
| tcg | ||
| ui | ||
| user | ||
| elf.h | ||
| glib-compat.h | ||
| qemu-common.h | ||
| qemu-io.h | ||