Hello,
I am trying to debug a Xenomai task through gdbserver over ethernet, with:
gdbserver host:12345 --attach 240
where 240 is the PID of the Xenomai real-time task I want to debug.
After connecting with the gdb client, running continuosly is fine, but if I put
a breakpoint and afterwards make the software execute an rt_event_wait call,
the system crashes (gdb client stuck, no more ethernet connection, no panic
message on the debug console serial port).
By going step by step with the debugger, the exact point of the problem can be
isolated:
int rt_event_wait(RT_EVENT *event,
unsigned long mask,
unsigned long *mask_r, int mode, RTIME timeout)
{
int ret;
ret = XENOMAI_SKINCALL5(__native_muxid,
__native_event_wait,
event, &mask, mode, XN_RELATIVE, &timeout);
if (ret)
return ret;
*mask_r = mask;
return 0;
}
with mode = EV_ANY, timeout is 10000 - 100000 ns about.
Showing the assembly code of the XENOMAI_SKINCALL5 macro:
0x64fc4e <rt_event_wait+42>: R3 = 0x0 (X); /* R3=0x0( 0) */
0x64fc50 <rt_event_wait+44>: R7.L = 0x22b; /* (555) R7=0x0x27022b(2556459) */
0x64fc54 <rt_event_wait+48>: JUMP.S 0x0x64fc60 <rt_event_wait+60>;
0x64fc56 <rt_event_wait+50>: R0 = P1;
0x64fc58 <rt_event_wait+52>: R1 = -0x55 (X); /* R1=0x0xffffffab(-85) */
0x64fc5c <rt_event_wait+56>: CC = R0 == R1;
0x64fc5e <rt_event_wait+58>: IF !CC JUMP 0x0x64fc9e <rt_event_wait+122>;
0x64fc60 <rt_event_wait+60>: [FP + -0x848] = R3;
0x64fc64 <rt_event_wait+64>: R1 = R6;
0x64fc66 <rt_event_wait+66>: R2 = P4;
0x64fc68 <rt_event_wait+68>: R0 = [P5];
0x64fc6a <rt_event_wait+70>: R0 = R0 | R7;
0x64fc6c <rt_event_wait+72>: P0 = R0;
0x64fc6e <rt_event_wait+74>: R0 = P3;
0x64fc70 <rt_event_wait+76>: EXCPT 0x0;
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
0x64fc72 <rt_event_wait+78>: P1 = R0;
0x64fc74 <rt_event_wait+80>: R0 = [FP + -0x848];
Execution crashes at EXCPT 0x0, which should be a system call, according to
Xenomai sources (syscall.h).
Xenomai version is 2.5.3, Linux 2.6.34.7, running on a Blackfin BF518 processor.
Note that everything works fine running the application without debugger.
Any hint?
Thank you very much in advance.
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