cquenel@polyslo.CalPoly.EDU (Chris Quenelle) (04/14/89)
DISCLAIMER! Flame me for an inappropriate posting if you have to, because I know that there are other channels for this. But it is so frustrating that I had to post. (It's 2:30 am, so my frustration tolerance level may be low :-). I'm sorta posting this because it's probably the fastest way to get Carl G.'s attention, and he will know who to poke with it (If you poke Roy Clark, Carl, say hi for me :-). I am writing a program on a Pyramid 98x. The program repeatedly calls ptrace() to single-step a process and read consecutive values of gr15 (the program counter). I am tracing a program that normally executes 16 instructions. We have the kernel debugger installed. The following problem manifests when I try to read the program counter (register gr15) from the process being traced. The problem: About 50% of the time, my program will cause our machine to drop into the kernel debugger and hang the entire system. (Luckily I'm in the same room as the console and can run over and hit "exit", and everything continues where it left off, the users just get hung for few seconds.) Anyway, the console says: Sys debug (cpu 0): unexpected step call from (ff005274) _syscall Pid 2daf (proc[94]) [cpyr], inode 3c18, dev 818 <dbg> exit "cpyr" is the name of the program being traced. The machine seems to hang when I try to read the gr15 value after executing the ret instruction at 00000080. If I continue from the kernel debugger, everything finishes okay. I get a trace of 00000068, 006c, 0070 and then the process exits. (...) 00000060: 4040003e _exit: call __cleanup,tr14 00000068: 01000431 movw pr0,tr1 0000006c: 11000070 movw $1,tr0 00000070: 2060003e callk $0,tr14 00000078: 00000000 halt (...) 00000080: 50900fc0 __cleanup: ret tr15,(gr0) --- 00000084: 00000000 halt Question: Will the problem go away if we un-install the kernel debugger, or will the machine just crash ? --chris Nobody said computers were going to be polite! -- @---@ ----------------------------------------------------------------- @---@ \. ./ |cquenel@polyslo.calpoly.edu It is inconceivable that this could| \. ./ \ / |be due to anything but nuclear processes. -- Fleischmann & Pons| \ / ==o== ----------------------------------------------------------------- ==o==