On Fri, 30 Aug 2013, Catalin Marinas wrote:
My position for the arm64 kernel support is to use the PSCI and implement the cluster power synchronisation in the firmware. IOW, no MCPM in the arm64 kernel :(. To help with this, ARM is going to provide a generic firmware implementation that SoC vendors can expand for their needs.
I am open for discussing a common API that could be shared between MCPM-based code and the PSCI one. But I'm definitely not opting for a light-weight PSCI back-end to a heavy-weight MCPM implementation.
Also note that IKS won't be supported on arm64.
I find the above statements a bit rigid.
While I think the reasoning behind PSCI is sound, I suspect some people will elect not to add it to their system. Either because the hardware doesn't support all the necessary priviledge levels, or simply because they prefer the easiest solution in terms of maintenance and upgradability which means making the kernel in charge. And that may imply MCPM. I know that ARM would like to see PSCI be adopted everywhere but I doubt it'll be easy.
In other words, if someone does the work to port MCPM to ARM64 and properly abstract the common parts with ARM32 then I don't see why you should refuse merging it.
That being said, it is normally those people who need it who should put resources forward to do that work. Linaro members needed it on ARM32 and this is why this work came out of Linaro initially.
Nicolas