l2cr= command line and bogomips

Hi list,

For all those with G3-upgraded machines booting directly via OF, here
is a small patch that actually enables the 'l2cr=' kernel command line
option.

Paul, if you agree, can you add this to your tree? Thanks.

The code to handle the option was present; but it was never called. I've
also made it more secure when enabling the cache.

The main reason I wanted to have this as a command line option is to
get tha cache enabled _before_ calculating the bogomips value, in order
to get the delay loop calibrated for a correct value, which is not the
case if you enable the cache later only (via /proc/sys/kernel/l2cr).

However, I've noticed that in 2.3 the bogomips value is 'correct'
whether the cache is enabled or not, whereas in 2.2 it varies from
single to double without/with cache.

Any explanation? Is the loop tighter now, so it runs in L1? Does 2.3
always enable the cache (but how does it know the correct settings
then)?

Michel

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