mem_ap: allow GDB connections

The target mem_ap is a convenient way to access buses, memory and
peripherals behind an ARM AP.
The current implementation provides only access through OpenOCD
commands, because GDB remote protocol has to interact with a CPU
and has to operate on CPU states and registers.
Using GDB to access the memory is welcome, because GDB can resolve
the symbol's address from an ELF file and can nicely display the
content of complex struct and data types.

Extend mem_ap target with the bare minimal support for a remote
GDB connection, by emulating a fake basic ARM core. It means that
only a GDB that has support for ARM can be used (either 'aarch64',
'arm' or 'multiarch' GDB). This is not seen as a big limitation,
because the mem_ap target is mainly used on ARM based devices.

Add a minimalist register description for the fake CPU.
Fill the field 'debug_reason' as expected by GDB server.
Call the target halted event to reply to GDB halt requests.

For backward compatibility, don't open the GDB port by default. If
needed, it has to be specified at 'target create' or 'configure'
with the flag '-gdb-port'.

Change-Id: I5a1b7adb749746516f5d4ffc6193c47b70132364
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/6034
Tested-by: jenkins

0 files changed, 0 insertions, 0 deletions