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SubjectRe: Where to call L2 cache enabling code from?
On Friday 14 April 2006 11:46 am, Alan Cox wrote:
> On Gwe, 2006-04-14 at 11:05 -0400, Steve Snyder wrote:
> > I have a machine in which the BIOS does not enable the Pentium3's L2
> > cache at boot time. At what point in the kernel init process
> > can/should I call the code to enable the cache?
> What part of the cache setup is not done correctly ? The mtrr registers
> or other things ?

It's not that the kernel is failing in any respect. The BIOS simply does
not enable the on-CPU L2 cache at power-on. (The machine originally
shipped with a Pentium2, and doesn't know how to enable the L2 cache on
the Pentium3 that is now running in it.)

I've got a small device driver that enables the L2 cache. It works fine
when build as a module and loaded after booting has completed. My goal
is to move the code into the kernel so that it is run early in the kernel
init process. I expect that having the L2 cache go from "0KB" to 256KB
will improve boot time greatly, as well as informing the kernel from the
get-go of the true capabilities of this processor.

Getting the code into the kernel image is a no-brainer. But once it is
built into the kernel, at what point should I call it?

Thanks for the response.
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