On Tue, Feb 19, 2019 at 9:59 PM Like Xu [off-list ref] wrote:

quoted

-/* leaf 0xb sub-leaf types */
+/* extended topology sub-leaf types */
  #define INVALID_TYPE        0
  #define SMT_TYPE    1
  #define CORE_TYPE   2
+#define DIE_TYPE     5

This patch set is going to export die topology via sysfs
while the extended topology sub-leaf type could be one of followings:
SMT/Core/Module/Tile/Die according to CPUID.1F from SDM.

Why not choose to export module/tile topology as well?

Excellent question.  (and thank you for reading the SDM:-)

While it is true that there are shipping products with
software-visible CPU modules and tiles,
they shipped before this mechanism was available.  As a result, there
are currently zero
products that use this mechanism to enumerate modules and tiles.  If
future products
have software-visible modules and tiles, and they choose to use this mechanism,
we can add support for them.  But I do not advocate adding code to the kernel
"just in case".

In contrast, the need to support multi-die/package products as soon as
possible is quite clear.

thanks,
Len Brown, Intel Open Source Technology Center