From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <393C0FA3.9208BAE1@embeddededge.com> Date: Mon, 05 Jun 2000 16:37:55 -0400 From: Dan Malek MIME-Version: 1.0 To: Murray Jensen CC: Daniel Wu , linuxppc-embedded@lists.linuxppc.org Subject: Re: 8xx MMU Table Walk Base (was Re: kernel crashes at InstructionTLBMiss ) References: <21966.960193171@msa.cmst.csiro.au> Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Murray Jensen wrote: > Here we come to a dilemma that I have had since I started with this stuff. > I have never been able to get an 8xx kernel running without adding a patch > to update the Table Walk Base register at the time that a new mm context is > activated. After reading your diatribe perhaps I should provide a little information. There are many subtle changes to context switching that happen during the minor updates (which could be weekly). There are several patches floating around (and probably more kernel sources) that certainly are not correct. I don't know where you get your source code, but there are exactly two consistent and working kernel sources that I have ever provided. One is in ftp://linuxppc.cs.nmt.edu/pub/linuxppc/embedded, the mpc8xx-2.2.13.tgz tarball. A better and completely up to date kernel is in ftp.mvista.com/pub/CDK/wip/ppc_8xx/RPMS (along with everything else to build an 8xx embedded system). Everyone should be using the kernel from MontaVista, and if something isn't in there that you want, send me patches against that. There are patches posted against that original tarball, and make sure you are not mixing kernel versions and patches. Finally, lots of bugs associated with porting to new hardware manifest themselves as "problems" in any VM related function. Since many people don't understand the subtle interactions of all of these functions (as evidenced by your message) you become convinced the problem is associated with this complexity and fail to unravel the clues to the real cause. This could be as simple as intrusive debugging hardware, some silicon bug not understood, or prototype hardware not working correctly. There are lots of products and systems in development running this software, so you have to approach this generic software from the assumption that it is first likely to be working. You seldom hear from those people. Are there possible bugs? Sure, and you have to provide minimal information for the rest of us to help out. Where did you get the sources? What patches did you apply? What are your hardware details? What modifications did you make? As for 2.4.xx, the 8xx still doesn't work correctly. However, I discovered it failed to work after the 403 additions, so I am now learning about the 403 in an effort to make everything live happily together again. Note, this has nothing to do with M_TWB...... -- Dan ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/