From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 1 Apr 2005 20:54:10 -0700 From: "Ronald G. Minnich" To: 9fans@cse.psu.edu Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Subject: [9fans] ts7200 Topicbox-Message-UUID: 311d3256-ead0-11e9-9d60-3106f5b1d025 It boots and runs fine. I can drawterm into it. IF ... l2 pte does not enable caching. I am caching the kernel text and data space (I just enable caching in the 1 Mbyte L1 PTE for 2 MB of kernel text + data; and the conf.base1 starts at the next MB boundary) and that is fine. Here's the fun part. I have boot.c fork and exec /boot/rc. So I have an rc prompt. If caching is enabled, all rc system calls run fine until the first Rfork from rc. In other words, all the RTC clock and OS clock interrupts are fine, running at 50hz or so, all the page fault activity from rc parent and child are fine, fine fine ... until the first syscall by the parent. The parent then explodes. Possibilities: 1. mmuswitch is not working. But I've ripped off the linux code for cache writeback/invalidate, and it sure looks right at present. I can send code to this list if there is interest. 2. The more interesting one. Something in the rfork/newproc path is setting something up wrong. Reason this could be it is that the two procs run fine until the first syscall ... that strikes me as odd. And, more interesting, there are a number of context switches back and forth between rc parent and rc child (I count 9) and they continue to run. I get the impression, looking at this, that they could run all day until a syscall and then they would die. If mmuswitch were really broken I would expect that to fail more quickly. But once the rc parent calls Pwrite (why that and not Await, I wonder) it's all over. And, even more odd, it's always repeatable. Same PC at the failure. This is typical: (syscall debug) rc:4 pc 15f20, Pwrite: 2014 9008 40 14604 rc: note: sys: trap: fault write va=0x0 pc=0x0001a Check out the bogus va,pc. Almost like the stack the kernel is seeing is junk. And the fd is certainly weird: 2014? Wonder if the process stacks are getting trashed up somehow -- but how would enabling caching affect this? ron p.s. I'm going to italy for the next 10 days (not as long as I'd like) but I'll try to catch up on this list and hope some smart person fixes my problem :-) Have a nice week, everyone, whereever you are.