[help] Crash with gdb on remote stub connection - 'find_inline_frame_state (ptid) == NULL' failed

Hi all,

I am trying to implement a remote stub for a series of bare metal MIPS 
processors (all running the same code). I'm modelling each processor as 
a separate thread in gdb. However, while trying to connect, I'm getting 
an internal gdb error, and I can't figure out why.

Here's the packet trace.

set remote debug 1
set pagination off
set target-async on
set non-stop on

Remote debugging using :8001
Sending packet: $qSupported:multiprocess+;qRelocInsn+#2a...Ack
Packet received: PacketSize=152;multiprocess+;QNonStop+
Packet qSupported (supported-packets) is supported
Sending packet: $Hgp0.0#ad...Ack
Packet received: OK
Sending packet: $QNonStop:1#8d...Ack
Packet received: OK
Sending packet: $qfThreadInfo#bb...Ack
Packet received: mp1.1,p1.2,p1.3,p1.4
Sending packet: $qAttached:1#fa...Ack
Packet received:
Packet qAttached (query-attached) is NOT supported
[New Thread 1]
remote_stop called
Sending packet: $vCont?#49...Ack
Packet received: vCont;c;C;s;S;t
Packet vCont (verbose-resume) is supported
Sending packet: $vCont;t:p1.1#f3...Ack
Packet received: OK
[New Thread 2]
[New Thread 3]
[New Thread 4]
Sending packet: $qsThreadInfo#c8...  Notification received: 
Stop:T00thread:p1.1;
Ack
Packet received: l
Sending packet: $qTStatus#49...Ack
Packet received:
Packet qTStatus (trace-status) is NOT supported
Sending packet: $?#3f...Ack
Packet received: T00thread:p1.1;thread:p1.2;thread:p1.3;thread:p1.4;
Sending packet: $vStopped#55...Ack
Packet received: T00thread:p1.1;thread:p1.2;thread:p1.3;thread:p1.4;
Sending packet: $vStopped#55...Ack
Packet received: OK
Sending packet: $qC#b4...Ack
Packet received: QCp1.1
Sending packet: $qOffsets#4b...Ack
Packet received: Text=0;Data=0;Bss=0
Sending packet: $qSymbol::#5b...Ack
Packet received: OK
Packet qSymbol (symbol-lookup) is supported
(gdb) Sending packet: $Hgp1.4#b2...Ack
Packet received: OK
Sending packet: $mbfc00010,4#e9...Ack
Packet received: 409df800

[Thread 4] #4 stopped.
nmi_starts () at crt0.S:75
75        mtc0    $sp, CP0_DESAVE // save existing sp (sim.vulnerable X's ?)
Sending packet: $mbfc00010,4#e9...Ack
Packet received: 409df800
/home/chrisb/gdb/dev/view/gdb-7.7.1/gdb/inline-frame.c:341: 
internal-error: skip_inline_frames: Assertion `find_inline_frame_state 
(ptid) == NULL' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) 
/home/chrisb/gdb/dev/view/gdb-7.7.1/gdb/inline-frame.c:341: 
internal-error: skip_inline_frames: Assertion `find_inline_frame_state 
(ptid) == NULL' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.


Does anyone have any ideas as to why this might be happening?

Thanks a lot,
Chris Bainbridge