Re: [PATCH 1/1] powerpc: fix missing L2 cache size in /sys/devices/system/cpu

On Tue, 2015-02-10 at 11:12 +1100, Benjamin Herrenschmidt wrote:

On Mon, 2015-02-09 at 15:43 -0800, Dave Olson wrote:

quoted

Michael Ellerman [off-list ref] wrote:

quoted

On Mon, 2015-02-09 at 14:14 -0800, Dave Olson wrote:

quoted

From: Dave Olson <redacted>

Fix missing L2 cache size in /sys/devices/system/cpu/cpu0/cache/index2/size
This bug appears to be introduced in 2.6.29 by 93197a36a9c16a85fb24cf5a8639f7bf9af838a3.
The missing entry caused lscpu to error out on e500v2 devices, and probably others
 error: cannot open /sys/devices/system/cpu/cpu0/cache/index2/size: No such file or directory
The DTS files we see use cache-size for the unified L2 cache size, not d-cache-size

Can you convince me that this is not going to break other machines that have
"d-cache-size" but not "cache-size"?

I'm unable to find any dts file that uses d-cache-size for the L2
unified cache.  All in the powerpc tree in arch/powerpc/boot/dts/*
are using cache-size in the L2 description for the cache size.

As best as I can tell from looking around, this is universal.

It may be universal for embedded machines using DTS in the kernel tree
but it's definitely not true of any Mac or server machine (from which
there is no DTS in the kernel as we get the DT from the firmware).

Right.

$ grep machine /proc/cpuinfo 
machine		: PowerNV 8247-22L

$ lsprop /proc/device-tree/cpus/l2-cache@20000020
name             "l2-cache"
status           "okay"
reg              20000020 (536870944)
phandle          00000005
linux,phandle    00000005
l2-cache         00000006
i-cache-size     00080000 (524288)
i-cache-sets     00000008
device_type      "cache"
d-cache-size     00080000 (524288)
d-cache-sets     00000008
cache-unified   


cheers