I'm trying to track down a problem where it seems that a page fault is causing a lockup on my machine. I am running on a PowerPC with Linux version 2.6.33.5 and Xenomai 2.5.4, but also saw the same thing with Xenomai 2.5.3.
What I am doing is mmaping a FPGA on the parallel bus in my task initialization. Later on I have a interrupt loop which uses rt_intr_wait to service some FPGA stuff. On access to some of my FPGA mapped registers I get a page fault which causes a lockup. I'm guessing there is some interaction going on with the rt_intr_wait and the fault exception. If I prefault the map by reading some of the registers before the loop it is ok. If I change the rt_intr_wait to a timed loop using rt_wait_period and don't prefault the registers it is ok. If I enable T_WARNSW I get a SIGXCPU when it tries to access the mapped registers. I don't necessarily care that it faults there so I don't want to have to prefault like I am doing. If I enable some of the debugging options I end up with the following exception dump: ----------- [ 23.623184] Xenomai: Switching to secondary mode after exception #769 from user-space at 0xff187ac (pid 586) [ 23.634273] Xenomai: Switching to secondary mode after exception #769 from user-space at 0xff187ac (pid 587) [ 23.653414] Xenomai: Switching to secondary mode after exception #769 from user-space at 0xff187ac (pid 592) [ 23.675243] Xenomai: Switching dsp_task to secondary mode after exception #769 from user-space at 0x10016634 (pid 595) [ 24.456360] Xenomai: Switching dsp_task to secondary mode after exception #769 from user-space at 0x10002d28 (pid 595) [ 24.467285] I-pipe: Detected illicit call from domain 'Xenomai' [ 24.467300] <3> into a service reserved for domain 'Linux' and below. [ 24.480199] Xenomai: Switching dsp_task to secondary mode after exception #1792 in kernel-space at 0xc0062f48 (pid 595) [ 24.491109] Oops: Exception in kernel mode, sig: 5 [#1] [ 24.496258] PREEMPT MPC5121 BE [ 24.499300] Modules linked in: lpcmem axe immmem [ 24.503912] NIP: c0062f48 LR: c0025b0c CTR: c01be5b0 [ 24.508870] REGS: c7bc3c60 TRAP: 0700 Not tainted (2.6.33.5) [ 24.514775] MSR: 00021032 <ME,CE,IR,DR> CR: 24000422 XER: 20000000 [ 24.521127] TASK = c7b30550[595] 'dsp_task' THREAD: c7bc2000 [ 24.526600] GPR00: 00000001 c7bc3d10 c7b30550 c03ac1c0 00002a39 ffffffff c0360000 c03ac1c0 [ 24.534946] GPR08: 00000000 000028ff 00002900 c0360000 82000442 1003c7b8 00000001 c0360000 [ 24.543292] GPR16: c03b0000 c7bc3f50 00008000 c0300000 c03b0000 c0360000 00000003 c0360000 [ 24.551638] GPR24: c0360000 c7bc3d3c 0000009c c7bc2000 0000000f c7bc3d4b c039d918 00000001 [ 24.560180] NIP [c0062f48] __ipipe_unstall_root+0x34/0x80 [ 24.565564] LR [c0025b0c] vprintk+0x340/0x444 [ 24.569895] Call Trace: [ 24.572336] [c7bc3d10] [c7bc3d4b] 0xc7bc3d4b (unreliable) [ 24.577729] [c7bc3d20] [c0025b0c] vprintk+0x340/0x444 [ 24.582770] [c7bc3db0] [c0026304] printk+0xb8/0x1f8 [ 24.587640] [c7bc3e00] [c006256c] ipipe_check_context+0xc4/0xcc [ 24.593555] [c7bc3e10] [c0299538] __down_interruptible+0xb4/0x148 [ 24.599643] [c7bc3e40] [c004799c] down_interruptible+0xcc/0xdc [ 24.605470] [c7bc3e60] [c0075acc] xnshadow_harden+0x64/0x248 [ 24.611114] [c7bc3e80] [c0075d4c] losyscall_event+0x9c/0x374 [ 24.616766] [c7bc3ed0] [c0063bc0] __ipipe_dispatch_event+0x98/0x1f0 [ 24.623025] [c7bc3f20] [c000bcf0] __ipipe_syscall_root+0x60/0x170 [ 24.629108] [c7bc3f40] [c00133e4] DoSyscall+0x20/0x5c [ 24.634151] --- Exception: c01 at 0xff19c94 [ 24.634158] LR = 0xff19c08 [ 24.641360] Instruction dump: [ 24.644318] 7c0802a6 90010014 7c0000a6 5400045e 7c000124 3d60c036 3d20c03b 814b2858 [ 24.652055] 3929c1c0 7d4a4a78 312affff 7c095110 <0f000000> 3d60c036 38600000 392b14f8 [ 24.660058] ------------[ cut here ]------------ [ 24.664600] kernel BUG at kernel/ipipe/core.c:311! [ 24.669413] ---[ end trace ca02c1a54b14d664 ]--- [ 24.674021] note: dsp_task[595] exited with preempt_count 1 _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
