This commit adds implementation of GDB stub for 32-bit ARM. It has been
tested only on the Zynq-7000 SoC and I would like to get any feedback
from others.
The stub still has these issues:
- To implement single stepping, it uses instruction address mismatch
breakpoint, as recommended in ARMv7 reference. The breakpoint control
register is configured (the state control fields) for the "PL0,
Supervisor and System modes only" option. Otherwise the breakpoint
would also halt the processor in abort mode, in which the stub loop
runs. Zephyr kernel runs in the system mode. This works well until the
kernel enables interrupts, as interrupt handlers typically run in
Supervisor mode. Single stepping therefore sometimes "catches" a
handler instead of the next application instruction. I have not tried
User mode, because Cortex-A SoCs do not appear to have the
ARCH_HAS_USERSPACE flag.
Cc: Michal Sojka <michal.sojka@cvut.cz>
Signed-off-by: Marek Vedral <marek.vedral@gmail.com>
93a4287115