> >On Fri, Oct 8, 2010 at 12:55 AM, Nicolas Pitre <nicolas.pi...@linaro.org> wrote: >On Thu, 7 Oct 2010, Vishwanath Sripathy wrote: > >> Hi All, >> >> Purpose of this email is to debate on the pros and cons of having a common >> ARM context save/restore code. >> Currently each SOC has its own way of saving/restoring ARM registers and >> there has been a proposal to have a common code for the same instead of >> duplicating the same in different places. > >Hmmmmm, what? > >Could you elaborate? I'm afraid I'm not following you. > >The kernel as I know it has a common code path to save/restore registers >on context switch simply because all SOCs that I'm aware of all have the >same general registers to save/restore on context switch. > >There are exceptions for some specialized registers, such as the XScale >WMMX registers, the Cirrus MaverickCrunch registers, the VFP registers >or the emulated FPA registers, etc. But those are nicely abstracted >away from the common code through runtime registered thread notifier >callbacks. I think what you are referring to is General Purpose ARM Registers which I agree are saved whenever there is a context switch. What I am talking here is other ARM registers like various Auxiliary Control regs (refer to arch/arm/mach_omap2/sleep34xx.s for complete details) which are completely lost when MPU enters OFF state in CPU Idle/suspend path.
Vishwa > > >Nicolas
_______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
