Re: ICTC control (was: tiBook CPU speed)

[Michel Lanners <mlan@cpu.lu>]

On   6 Aug, this message from Benjamin Herrenschmidt echoed through cyberspace:
> Something else we may want to
> implement is a way (sysctl ?) to control the ICTC (instruction cache
> throttling). This has the effect of slowing down instruction fetching
> by the CPU and lowering it's temperature & power consumption.

I have most of the code for this ready; but it was for 2.2 kernels
(nothing fancy; just a copy of the l2cr bit :-).

I've looked at how one can integrate it into 2.4. We'd need a sysctl
number in kernel/sysctl.[c,h], and a function handling the gory details.

We could move the l2cr sysctl out of ppc_htab.c together with ICTC
control into a separate ppc_sysctl.c file.

What remains is to decide whether ICTC gets a separate feature bit in
cputable.[c,h].

Cheers

Michel

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