From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [parisc-linux] PA8800/ZX1 support committed to 2.6.7-rc2-pa2 Date: 05 Jun 2004 16:19:24 -0500 Message-ID: <1086470366.1999.36.camel@mulgrave> References: <20040604202546.GC18574@colo.lackof.org> <20040605065126.GA28343@colo.lackof.org> <1086444652.1999.20.camel@mulgrave> <20040605210515.GA8098@colo.lackof.org> Mime-Version: 1.0 Content-Type: text/plain Cc: PARISC list To: Grant Grundler Return-Path: In-Reply-To: <20040605210515.GA8098@colo.lackof.org> List-Id: parisc-linux developers list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: parisc-linux-bounces@lists.parisc-linux.org On Sat, 2004-06-05 at 16:05, Grant Grundler wrote: > Well, I can only point at the difference in cache size. The pa8800 only has a 750k/750k VIPT cache, that's smaller than my raven. The 32M L2 cache is PIPT, which doesn't suffer from aliasing or address remapping effects---in fact, the PA engineers probably arranged for a fdc not to flush it because there's no point; the only coherency problems the PIPT cache has is with I/O, which is supposed to be fully coherent in the ZX1, isn't it. Thus, we'd only pick up a caching problems like you describe from the VIPT caches. > > My money would be on an additional architectural requirement of the > > PA8800 (maybe even an existing PA one that the > that we don't respect. > > yes - and we've changed chipsets too. > > Any good ideas on how to prove IO is coherent? Well, yes, but not without driver magic. You program a device to take a piece of data in and rewrite it to a different buffer, then you compare buffers (making sure the first had a pattern in it and the second was completely clear). > It might be the same problem that Naresh described as "SCSI DMA problems". > I just happen to be using NFS Root instead. > > But I found one bug in Naresh's port that might explain his problem > (wasn't flushing IO TLB properly). It would be interesting to hear > if 2.6.7-rc2-pa3 works better for him. Well, it could be an I/O coherency problem, but if you have one of those, I'm surprised it boots at all. James _______________________________________________ parisc-linux mailing list parisc-linux@lists.parisc-linux.org http://lists.parisc-linux.org/mailman/listinfo/parisc-linux