nrf51.cpu -- clearing lockup after double fault

[matthiasbock]

Problem with commit ca76565:
Binary demo_leds.elf won't run on the target, neither on the QFAA nor the QFAC chip variant.

(gdb) monitor reset halt
target state: halted
target halted due to debug-request, current mode: Thread 
xPSR: 0xc0000000 pc: 0x4b11af00 msp: 0xb082b580
(gdb) c
Continuing.
nrf51.cpu -- clearing lockup after double fault

Program received signal SIGINT, Interrupt.
0xfffffffe in ?? ()
(gdb) i r
r0             0xffffffff       -1
r1             0xffffffff       -1
r2             0xffffffff       -1
r3             0xffffffff       -1
r4             0xffffffff       -1
r5             0xffffffff       -1
r6             0xffffffff       -1
r7             0xffffffff       -1
r8             0xffffffff       -1
r9             0xffffffff       -1
r10            0xffffffff       -1
r11            0xffffffff       -1
r12            0xffffffff       -1
sp             0xb082b560       0xb082b560
lr             0xfffffff9       -7
pc             0xfffffffe       0xfffffffe
xPSR           0xc1000003       -1056964605
(gdb) monitor reset halt
target state: halted
target halted due to debug-request, current mode: Thread 
xPSR: 0xc0000000 pc: 0x4b11af00 msp: 0xb082b580
(gdb) set $sp=0x20001000
Cannot access memory at address 0x0

[matthiasbock]

works with branch orchid-lamp, commit a28b339