hi,
i'm interesting w/t the light-weight PSCI backend for MCPM which reminded by Amit. When will ARM release related code to the community so that we can get know more well for it?
Just like Nico said, PSCI is a common framework and the the common framework will take related long time to be adopt, not only for ARM, also for the SoC companies. So if we can know more detailed info for PSCI's schedule, then we can decide we can follow PSCI in our own product or use MCPM for near term's product and switch to PSCI after it's ready.
Thx, Leo Yan
On 08/31/2013 10:30 PM, Roger Teague wrote:
Hi Nicolas, one of the ideas behind PSCI and the Generic Firmware apart from the obvious consolidation of methods is to ensure that partners have a framework for future expansion as the functionality of ARM IP increases.
With a common strategy we are much better placed to pipeline new functionality and other features into to software ecosystem.
We absolutely would never discourage innovation and perhaps alternatives but these will always lag what ARM is supporting purely because they will need any new IP to be public whereas we can work on Generic FW ahead of the curve.
So we're not being harsh but simply acknowledging how the product pipeline works
Hope this helps
Roger
Sent from yet another low power ARM device
On 31 Aug 2013, at 03:21, "Nicolas Pitre" nicolas.pitre@linaro.org wrote:
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
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