[parisc-linux] Re: [parisc-linux-cvs] linux carlos

[Grant Grundler]

On Thu, Aug 28, 2003 at 09:04:40AM +0200, Joel Soete wrote:
> Hi Grant,
> 
> >AFAIK, a cacheline will get loaded as "shared clean"
> >until someone writes to it - which is when the cacheline ping-pong
> >starts.
> 
> Mhh would it not request some kind of ipc between cpu for cache management?

no.
IIRC instructions for purging the cache are broadcast to other CPUs.

> But to avoid usage of cache would it be possible to access global kernel's
> variable with absolute addressing mode? Is it feasible?

Since the caches use virtual indices, it would make sense when using
physically addresses to bypass the cache. But I don't know if that's
really the case or not. I would expect that described in the PA2.0 Arch
book.

> btw scaning code related to SMP I find in smp.c a very draft of
> an 'ipi_init()' but unfortunately 'Ignore for now.  *May* need this
> "hook" to register IPI handler'..., interesting isn't it :).

I wrote that. ipi_init and comments can be deleted.
I haven't seen a need for ipi_init(). When I originally
implemented the SMP support I thought it might be.

The IPI handler is statically "hooked" (aka registered) in
	arch/parisc/kernel/irq.c:cpu_irq_actions[]

See ipi_interrupt() for IPI implementation.

> Is there any other platform inplementing such stuff (I try to scan 2.4 src
> but not found anywhere else) or some reference on to implement it?

it == ?
IPI is implemented.

grant