Red Hat ENTERPRISE LINUX 3 - SECURITY GUIDE, Manual

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322 Appendix D. gdb Remote Serial Protocol
win). The printable characters
$
,
#
,
+
and
-
or with a numeric value greater than 126 should not be
used.
Some remote systems have used a different run-length encoding mechanism loosely refered to as the
cisco encoding. Following the
*
character are two hex digits that indicate the size of the packet.
So:
"
0*
"
means the same as "0000".
The error response returned for some packets includes a two character error number. That number is
not well defined.
For any
command
not supported by the stub, an empty response (
$#00
) should be returned. That way it
is possible to extend the protocol. A newer gdb can tell if a packet is supported based on that response.
A stub is required to support the
g
,
G
,
m
,
M
,
c
, and
s command
s. All other
command
s are optional.
D.2. Packets
The following table provides a complete list of all currently defined
command
s and their corresponding
response
data
.
!
-- extended mode
Enable extended mode. In extended mode, the remote server is made persistent. The
R
packet is
used to restart the program being debugged.
Reply:
OK
The remote target both supports and has enabled extended mode.
?
-- last signal
Indicate the reason the target halted. The reply is the same as for step and continue.
Reply: (refer to Section D.3 Stop Reply Packets , for the reply specifications.
a
-- reserved
Reserved for future use.
Aarglen,argnum,arg,...
-- set program arguments (reserved)
Initialized
argv[]
array passed into program.
arglen
specifies the number of bytes in the hex
encoded byte stream
arg
. See
gdbserver
for more details.
Reply:
OK
E
NN
No other details.