specified register, but a pointer to the in-memory representation of
that value. The reason for this is twofold:
1. Not all registers can be represented by a register_t. In particular
FP registers fall in that category. Passing the new register value
by reference instead of by value makes this point moot.
2. When we receive a G or P packet, both are for writing a register,
the packet will have the register value in target-byte order and
in the memory representation (modulo the fact that bytes are sent
as 2 printable hexadecimal numbers of course). We only need to
decode the packet to have a pointer to the register value.
This change fixes the bug of extracting the register value of the P
packet as a hexadecimal number instead of as a bit array. The quick
(and dirty) fix to bswap the register value in gdb_cpu_setreg() as
it has been added on i386 and amd64 can therefore be removed and has
in fact been that.
Tested on: alpha, amd64, i386, ia64, sparc64
related to breakpoints and single stepping into SIGTRAP so gdb(1) knows
why the remote target has stopped. In particular, gdb(1) needs to know
if the reason is something of its own doing.
backend improves over the old GDB support in the following ways:
o Unified implementation with minimal MD code.
o A simple interface for devices to register themselves as debug
ports, ala consoles.
o Compression by using run-length encoding.
o Implements GDB threading support.
