[PATCH] Fix error when gdb connect to a stub that tracepoint is running[0/2]

[PATCH] Fix error when gdb connect to a stub that tracepoint is running[0/2]

[Hui Zhu]

Hi,

I found some error when I try to let GDB connect to a stub that have a 
tracepoint and it support insert tracepoint when trace is running, for 
example:
(gdb) info tracepoints
Num     Type           Disp Enb Address            What
1       tracepoint     keep y   0x0000000000400557 in main at 1.c:15
         collect $reg
(gdb) set disconnected-tracing on
(gdb) tstart
(gdb) disconnect
Trace is running and will continue after detach; detach anyway? (y or n) y
Ending remote debugging.
(gdb) target remote localhost:1234
Remote debugging using localhost:1234
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols 
found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Error in re-setting breakpoint 1: Target returns error code '01'.
Target returns error code '01'.
(gdb) disconnect
You can't do that when your target is `exec'
(gdb) quit
gdb ./a.out
(gdb) target remote localhost:1234
Remote debugging using localhost:1234
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols 
found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
0x00007ffff7ddcaf0 in ?? () from /lib64/ld-linux-x86-64.so.2
Trace is already running on the target.
Tracepoint 1 at 0x400557: file 1.c, line 15.
Target returns error code '01'.


This is because GDB try to insert this tracepoint to gdb stub part 
because this stub support inserted tracepoint when it running. but this 
behaveior have 2 trouble:
1. stub already have a treacepoint same with gdb part, if GDB try to 
re-inserted it, we will got a error.
2. Even if gdb part doesn't have this tracepoint, when it got this 
tracepoint from gdbstub part, it will try to insert this tracepoint to 
gdbstub when create_breakpoint.

So I fix this issue with 2 patches.

Thanks,
Hui

Re: [PATCH] Fix error when gdb connect to a stub that tracepoint is running[0/2]

[Yao Qi]

On 01/31/2012 10:04 AM, Hui Zhu wrote:
> (gdb) info tracepoints
> Num     Type           Disp Enb Address            What
> 1       tracepoint     keep y   0x0000000000400557 in main at 1.c:15
>         collect $reg
> (gdb) set disconnected-tracing on
> (gdb) tstart
> (gdb) disconnect
> Trace is running and will continue after detach; detach anyway? (y or n) y
> Ending remote debugging.
> (gdb) target remote localhost:1234
> Remote debugging using localhost:1234
> Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols
> found)...done.
> Loaded symbols for /lib64/ld-linux-x86-64.so.2
> Error in re-setting breakpoint 1: Target returns error code '01'.
> Target returns error code '01'.
> (gdb) disconnect
> You can't do that when your target is `exec'
> (gdb) quit
> gdb ./a.out
> (gdb) target remote localhost:1234
> Remote debugging using localhost:1234
> Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols
> found)...done.
> Loaded symbols for /lib64/ld-linux-x86-64.so.2
> 0x00007ffff7ddcaf0 in ?? () from /lib64/ld-linux-x86-64.so.2
> Trace is already running on the target.
> Tracepoint 1 at 0x400557: file 1.c, line 15.
> Target returns error code '01'.
> 

Yes, this is a bug.  It is better if we can convert these steps into a
.exp test case :).

-- 
Yao (齐尧)