Re: [Qemu-devel] [Qemu-ppc] [PATCH v3 2/2] target-ppc: Implement rtas_get_sysparm(PROCESSOR_MODULE_INFO)

[Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>]

David Gibson [david@gibson.dropbear.id.au] wrote:
| > Should we walk the /proc/device-tree/cpus/ tree and count only dirs with
| > device-type "cpu" (rather than relying on the pattern PowerPC,POWER*)?
| 
| Yes, I think you'll have to.
| 
Ok. Are we ok with the xscom check I have (copied below):

+static int kvmppc_count_sockets_chips_dt(int *num_sockets, int *num_chips)
+{
+    const char *chip_pattern = "/proc/device-tree/xscom@*/ibm,chip-id";
+    const char *module_pattern = "/proc/device-tree/xscom@*/ibm,hw-module-id";

---

I am not sure of a reliable way to detect number of chips besides the
xscom. I do see that sysfs has node entries:

	for i in `ls -d /sys/bus/cpu/devices/cpu*`; 
	> do
	> basename $i/node*
	> done | sort | uniq
	node0
	node1
	node16
	node17

which seems to correspond to

	$ lsprop /proc/device-tree/xscom@*/ibm,chip-id
	/proc/device-tree/xscom@3fc0000000000/ibm,chip-id
			 00000000
	/proc/device-tree/xscom@3fc0800000000/ibm,chip-id
			 00000001
	/proc/device-tree/xscom@3fc8000000000/ibm,chip-id
			 00000010 (16)
	/proc/device-tree/xscom@3fc8800000000/ibm,chip-id
			 00000011 (17)

but is that reliable?
> +
| > | 
| > | In a number of ways I'd actually prefer to move to /cpus/cpu@NNN in
| > | general, since that follows the OF generic names recommendation we
| > | follow for most other nodes.
| > 
| > Do you mean rename '/proc/device-tree/cpus/PowerPC,POWER8@NNN' to
| > /proc/device-tree/cpus/cpu@NNN?
| 
| Yes.  This is a firmware matter, so it's not something that can simply
| be changed everywhere, but it's the approach that I'd prefer to
| encourage for people making future machines and firmwares.

Sure. ppc64_cpu also seems to rely on '/proc/device-tree/cpus/PowerPC'
to count cores present and maybe there are other utilities that would
need to be updated.

Sukadev