can't gdb vkernel

[Nicolas Thery]

2008/7/3 Matthew Dillon <dillon at apollo.backplane.com>:
>
> :hey,
> :
> :when gdb'ing a vkernel, I run into this situation:
> :
> :     0 32061 23371   3 154   0 25348 24444 wait   SL    p1    0:00.34 gdb=
> :=20
> :kernel.debug
> :     0 32062 32061   0 152   0 1052908 18784 stop   TXL+  p1    0:00.11=20
> :kernel.debug
> :
> :this happens after mounting root, i.e. when init is run in the vkernel.=20
> :Seems that the first SIGSEGV is being delivered, kernel is stopped for=20
> :this purpose, but gdb never receives SIGCHLD, or rather wait doesn't retu=
> :rn?
> :
> :cheers
> :   simon
>
>    This happens to me all the time.  I haven't had time to track it down.
>
>    I usually work around it by gdb'ing the vkernel, and then quiting out
>    of gdb (which seems to restart the vkernel ok) instead of typing 'cont'.
>
>    Please, if you can find it, be my guest!

I'm looking into this.  There is a deadlock involving the gdb lwp and
2 vkernel lwps. I hope to have a clearer understanding and a fix this
week-end.