Jean,
Yes, it is basically doing the same stuff as the OMAP idle code, but in a more generic way. It is mostly C, with assembler helper functions.
I need to find out whether I can release the code.
Jon.
-----Original Message----- From: Jean Pihet [mailto:jean.pihet@newoldbits.com] Sent: 12 October 2010 11:48 To: Jon Callan Cc: linaro-dev@lists.linaro.org Subject: Re: Common ARM context save/restore code
Hi Jon,
That is a nice follow up to the OMAP idle code clean up, cf. http://lists.linaro.org/pipermail/linaro-dev/2010-October/001084.html. It would be nice to see how the code is organized and the impact of integrating it into the kernel.
Regards, Jean
On Tue, Oct 12, 2010 at 12:39 PM, Jon Callan Jon.Callan@arm.com wrote:
Vishwa,
I have a more-or-less complete set of example code for CPU context save/restore, currently supporting A5/A8/A9 and with planned support for Eagle.
It is structured as "firmware" at the moment, but it would be much better if it was integrated into the ARM Linux kernel. The idea is the kernel calls it from CPUidle, and it saves all CPU context and cuts the power. Then when power returns, it restores all CPU context and returns to the kernel as if nothing has happened.
It handles just the CPU and cluster context, which on A9mpcore includes MMU, GIC, VFP, SCU, L2cc, Debug, etc. It takes care of cleaning caches and entering/leaving the coherency domain. There is also support for TrustZone, but as you say that's quite platform-specific.
So we would need to integrate this with the SoC-specific code somehow.
Jon.
I work Tue/Wed/Fri only Jon Callan, Staff Software Engineer, Processor Division ARM Cambridge / +44 1223 400814
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