From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Mackerras MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Message-ID: <15612.5934.333737.934644@argo.ozlabs.ibm.com> Date: Tue, 4 Jun 2002 11:26:06 +1000 (EST) To: Dan Malek Cc: David Gibson , linuxppc-embedded@lists.linuxppc.org Subject: Re: CONFIG_PIN_TLB and telnet problems In-Reply-To: <3CFC0FDD.1060607@embeddededge.com> References: <20020531071550.GF16537@zax> <3CFC0FDD.1060607@embeddededge.com> Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Dan Malek writes: > As I mentioned in the first message, I suspect the problem is with the > multiple mapping/access of data in the pinned and remapped areas. Linux > tends to allocate memory from the high end down, so if you consistent_alloc() > some space on large memory systems, you are just remapping the attributes > of a page. If you do this on memory that is also covered by a large page, > sometimes you will get the access through this large page, and others through > an alternate mapping, which I believe confuses the MMU/cache with different > attributes (which I was assured wouldn't cause problems on 4xx). We have reproduced the problem using a ramdisk root and loopback, with the ethernet disabled, so the only I/O device that is active is the serial port, which doesn't use DMA. So it doesn't look like it is anything to do with DMA or with consistent_alloc. Paul. ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/