The cpu-map DT entry in ARM can describe the CPU topology in much better way compared to other existing approaches. RISC-V can easily adopt this binding to represent its 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 significant 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. There was an opportunity to unify topology data structure for ARM32 done by patch 3/4. But, I refrained from making any other changes as I am not very well versed with original intention for some functions that are present in arch_topology.c. I hope this patch series can be served as a baseline for such changes in the future. The patches have been tested for RISC-V, ARM64, ARM32 & compile tested for x86. >From Jeremy, "I applied these to 5.2rc2, along with my PPTT/MT change and verified the system & scheduler topology/etc on DAWN and ThunderX2 using ACPI on arm64. They appear to be working correctly. so for the series, Tested-by: Jeremy Linton <jeremy.linton@xxxxxxx>" The socket change[2] is also now part of this series. [1] https://lkml.org/lkml/2018/11/6/19 [2] https://lkml.org/lkml/2018/11/7/918 This patch series can also be found at https://github.com/atishp04/linux/tree/5.2-rc6_topology QEMU changes for RISC-V topology are available here https://lists.nongnu.org/archive/html/qemu-devel/2019-06/msg05974.html HiFive Unleashed DT with topology node is available here. https://patchwork.kernel.org/patch/11014313/ Changes from v7->v8 1. Regenerated the patch series without -b option in git format-patch. Without that, git apply from email won't work because ignored space changes. Changes from v6->v7 1. Added socket to HiFive Unleashed topology example. 2. Added Acked-by & Reviewed-by. Changes from v5->v6 1. Added two more patches from Sudeep about maintainership of arch_topology.c and Kconfig update. 2. Added Tested-by & Reviewed-by 3. Fixed a nit (reordering of variables) Changes from v4-v5 1. Removed the arch_topology.h header inclusion from topology.c and arch_topology.c file. Added it in linux/topology.h. 2. core_id is set to -1 upon reset. Otherwise, ARM topology store function does not work. Changes from v3->v4 1. Get rid of ARM32 specific information in topology structure. 2. Remove redundant functions from ARM32 and use common code instead. Changes from v2->v3 1. Cover letter update with experiment DT for topology changes. 2. Added the patch for [2]. Changes from v1->v2 1. ARM32 can now use the common code as well. Atish Patra (4): dt-binding: cpu-topology: Move cpu-map to a common binding. cpu-topology: Move cpu topology code to common code. arm: Use common cpu_topology structure and functions. RISC-V: Parse cpu topology during boot. Sudeep Holla (3): Documentation: DT: arm: add support for sockets defining package boundaries base: arch_topology: update Kconfig help description MAINTAINERS: Add an entry for generic architecture topology .../topology.txt => cpu/cpu-topology.txt} | 256 ++++++++++----- MAINTAINERS | 7 + arch/arm/include/asm/topology.h | 20 -- arch/arm/kernel/topology.c | 60 +--- arch/arm64/include/asm/topology.h | 23 -- arch/arm64/kernel/topology.c | 303 +----------------- arch/riscv/Kconfig | 1 + arch/riscv/kernel/smpboot.c | 3 + drivers/base/Kconfig | 2 +- drivers/base/arch_topology.c | 298 +++++++++++++++++ include/linux/arch_topology.h | 26 ++ include/linux/topology.h | 1 + 12 files changed, 514 insertions(+), 486 deletions(-) rename Documentation/devicetree/bindings/{arm/topology.txt => cpu/cpu-topology.txt} (66%) -- 2.21.0
