From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 28 Aug 2003 09:12:16 -0600 From: Grant Grundler To: Joel Soete Cc: parisc-linux@lists.parisc-linux.org Subject: Re: [parisc-linux] Re: [parisc-linux-cvs] linux carlos Message-ID: <20030828151216.GA23430@dsl2.external.hp.com> References: <3F4D798800000061@ocpmta7.freegates.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <3F4D798800000061@ocpmta7.freegates.net> Sender: parisc-linux-admin@lists.parisc-linux.org Errors-To: parisc-linux-admin@lists.parisc-linux.org List-Help: List-Post: List-Subscribe: , List-Id: parisc-linux developers list List-Unsubscribe: , List-Archive: 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