On Tue, 2024-06-18 at 18:53 -0700, Pawan Gupta wrote:
On Tue, Jun 18, 2024 at 02:49:10PM +0200, Brice Goglin wrote:But you still have to look at frequency or caches as there are Low
Le 17/06/2024 à 11:11, Pawan Gupta a écrit :Sure, if it helps userspace.
Hi,
This series adds support for CPU-type (CPUID.1A.EAX[31-24] on
Intel) to
differentiate between hybrid variants P+E, P-only, E-only that
share the
same Family/Model/Stepping. One of the use case for CPU-type is
the
affected CPU table for CPU vulnerabilities, which can now use the
CPU-type
to filter the unaffected variants.
* Patch 1 adds cpu-type to CPU topology structure and introduces
topology_cpu_type() to get the CPU-type.
* Patch 2-4 replaces usages of get_this_hybrid_cpu_type() with
topology_cpu_type().
* Patch 5-7 Updates CPU-matching infrastructure to use CPU-type.
* Patch 8 cleans up the affected CPU list.
* Patch 9 uses the CPU-type to exclude P-only parts from the RFDS
affected
list.
Hello
Is there still a plan to expose this info in sysfs?
Userspace currently uses frequencies to guess which cores are E orThere can be many ways to expose this information in sysfs. Like this
P.
Intel sent some patches several years ago [1], but they got
abandoned
nowhere as far as I know. There was also some discussion about
using a
"capacity" field like ARM does, but IIRC Intel didn't like the idea
in
the end.
...
[1] https://lkml.org/lkml/2020/10/2/1208... exposes /sys/devices/system/cpu/types which, in hybrid parts,
creates a
subdirectory for each type of CPU. Each subdirectory contains a CPU
list
and a CPU map that user space can query.
The other way is to expose the CPU-type in a file:
/sys/devices/system/cpu/cpuN/type
that could return the CPU-type of the CPU N. Is there a preference?
power E-cores which will have same type but different capabilities.