How to disable GDB backtrace new behavior of including disassembly in backtrace ?

Simon Marchi simark@simark.ca
Fri Dec 13 19:48:00 GMT 2019


On 2019-12-13 7:09 a.m., William Tambe wrote:
> How to disable GDB backtrace new behavior of including disassembly in
> backtrace ?
> 
> I have built GDB 8.3 and here is an example of output that I now see:
> 
> bt
> #0  0x0005ed42 in set_next_entity (se=<optimized out>,
> cfs_rq=<optimized out>) at /linux/kernel/sched/fair.c:6844
>    0x0005ed38 <pick_next_task_fair+492>:        80 74   li8 %7, 0x4 # 4
>    0x0005ed3a <pick_next_task_fair+494>:        b8 70   add %7, %sp
>    0x0005ed3c <pick_next_task_fair+496>:        ea 37   ld32 %3, %7
>    0x0005ed3e <pick_next_task_fair+498>:        c7 13   cpy %1, %3
>    0x0005ed40 <pick_next_task_fair+500>:        92 10   inc8 %1, 32 # 0x20
> => 0x0005ed42 <pick_next_task_fair+502>:        ea 11   ld32 %1, %1
>    0x0005ed44 <pick_next_task_fair+504>:        ea 50   ld32 %5, %sp
>    0x0005ed46 <pick_next_task_fair+506>:        e0 d0   gip %sr
>    0x0005ed48 <pick_next_task_fair+508>:        a2 d0 4e 00 00 00
>  inc32 %sr, 78 # 0x4e
>    0x0005ed4e <pick_next_task_fair+514>:        d1 1d   jnz %1, %sr
> #1  pick_next_task_fair (rq=<optimized out>, prev=<optimized out>,
> rf=<optimized out>) at /linux/kernel/sched/fair.c:6844
> 
> Using an earlier version of GDB would have just shown two lines
> without disassembly; ie:
> 
> bt
> #0  0x0005ed42 in set_next_entity (se=<optimized out>,
> cfs_rq=<optimized out>) at /linux/kernel/sched/fair.c:6844
> #1  pick_next_task_fair (rq=<optimized out>, prev=<optimized out>,
> rf=<optimized out>) at /linux/kernel/sched/fair.c:6844
> 
> How can I restore the GDB old behavior when using backtrace ?
> 

Hi William,

I have never seen this behavior.  It's either a setting I have never
encountered, or a Python script you have loaded that is providing this
functionality (e.g. with a frame-filter).

Are you able to reproduce this behavior with another program?  If so, could
you send a small reproducer (small source snippet to compile + GDB commands),
we can try it and tell you if we see the same behavior.

Simon



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