On 12/7/18 5:45 AM, Morten Rasmussen wrote:
Hi,
On Thu, Nov 29, 2018 at 03:28:16PM -0800, Atish Patra wrote:
The cpu-map DT entry in ARM64 can describe the CPU topology in
much better way compared to other existing approaches. RISC-V can
easily adopt this binding to represent it's own CPU topology.
Thus, both cpu-map DT binding and topology parsing code can be
moved to a common location so that RISC-V or any other
architecture can leverage that.
The relevant discussion regarding unifying cpu topology can be
found in [1].
arch_topology seems to be a perfect place to move the common
code. I have not introduced any functional changes in the moved
code. The only downside in this approach is that the capacity
code will be executed for RISC-V as well. But, it will exit
immediately after not able to find the appropriate DT node. If
the overhead is considered too much, we can always compile out
capacity related functions under a different config for the
architectures that do not support them.
The patches have been tested for RISC-V and compile tested for
ARM64 & x86.
The cpu-map bindings are used for arch/arm too, and so is
arch_topology.c. In fact, it was introduced to allow code-sharing
between arm and arm64. Applying patch three breaks arm.
Moving the DT parsing to arch_topology.c we have to unify all three
architectures. Be aware that arm and arm64 have some differences in how
they detect cpu capacities. I think we might have to look at the split
of code between arch/* and arch_topology.c again :-/
Morten
Thank you for bringing this up. I will send a new version and make sure
that it works on arm32 as well.
Regards,
Atish
