The following table provides a complete list of all currently defined commands 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
?
-- last signal
Indicate the reason the target halted. The reply is the same as for step and continue.
Reply:
See Stop Reply Packets, for the reply specifications.
a
-- reserved
A
arglen,
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
b
baud -- set baud (deprecated)
Change the serial line speed to baud.
JTC: When does the transport layer state change? When it's received, or after the ACK is transmitted. In either case, there are problems if the command or the acknowledgment packet is dropped.
Stan: If people really wanted to add something like this, and get
it working for the first time, they ought to modify ser-unix.c to send
some kind of out-of-band message to a specially-setup stub and have the
switch happen "in between" packets, so that from remote protocol's point
of view, nothing actually happened.
B
addr,mode -- set breakpoint (deprecated)
Set (mode is S
) or clear (mode is C
) a
breakpoint at addr. This has been replaced by the Z
and z
packets.
c
addr -- continue
addr is address to resume. If addr is omitted, resume at current address.
Reply:
See Stop Reply Packets, for the reply specifications.
C
sig;
addr -- continue with signal
Continue with signal sig (hex signal number). If
;
addr is omitted, resume at same address.
Reply:
See Stop Reply Packets, for the reply specifications.
d
-- toggle debug (deprecated)
Toggle debug flag.
D
-- detach
Detach GDB from the remote system. Sent to the remote target before GDB disconnects.
Reply:
no response
e
-- reserved
E
-- reserved
f
-- reserved
F
-- reserved
g
-- read registers
Read general registers.
Reply:
XX...
g
packet are
determined by the GDB internal macros REGISTER_RAW_SIZE
and REGISTER_NAME macros. The specification of several standard
g
packets is specified below.
E
NN
G
XX... -- write regs
See read registers packet, for a description of the XX... data.
Reply:
OK
E
NN
h
-- reserved
H
ct... -- set thread
Set thread for subsequent operations (m
, M
, g
,
G
, et.al.). c depends on the operation to be performed: it
should be c
for step and continue operations, g
for other
operations. The thread designator t... may be -1, meaning all
the threads, a thread number, or zero which means pick any thread.
Reply:
OK
E
NN
i
addr,
nnn -- cycle step (draft)
Step the remote target by a single clock cycle. If ,
nnn is
present, cycle step nnn cycles. If addr is present, cycle
step starting at that address.
I
-- signal then cycle step (reserved)
See step with signal packet. See cycle step packet.
j
-- reserved
J
-- reserved
k
-- kill request
FIXME: There is no description of how to operate when a specific
thread context has been selected (i.e. does 'k' kill only that
thread?).
K
-- reserved
l
-- reserved
L
-- reserved
m
addr,
length -- read memory
Read length bytes of memory starting at address addr. Neither GDB nor the stub assume that sized memory transfers are assumed using word alligned accesses. FIXME: A word aligned memory transfer mechanism is needed.
Reply:
XX...
E
NN
M
addr,length:
XX... -- write mem
Write length bytes of memory starting at address addr. XX... is the data.
Reply:
OK
E
NN
n
-- reserved
N
-- reserved
o
-- reserved
O
-- reserved
p
n... -- read reg (reserved)
Reply:
r....
P
n...=
r... -- write register
Write register n... with value r..., which contains two hex digits for each byte in the register (target byte order).
Reply:
OK
E
NN
q
query -- general query
Request info about query. In general GDB queries have a
leading upper case letter. Custom vendor queries should use a company
prefix (in lower case) ex: qfsf.var
. query may optionally
be followed by a ,
or ;
separated list. Stubs must ensure
that they match the full query name.
Reply:
XX...
E
NN
Q
var=
val -- general set
Set value of var to val.
See general query packet, for a discussion of naming conventions.
r
-- reset (deprecated)
Reset the entire system.
R
XX -- remote restart
Restart the program being debugged. XX, while needed, is ignored. This packet is only available in extended mode.
Reply:
no reply
R
packet has no reply.
s
addr -- step
addr is address to resume. If addr is omitted, resume at same address.
Reply:
See Stop Reply Packets, for the reply specifications.
S
sig;
addr -- step with signal
Like C
but step not continue.
Reply:
See Stop Reply Packets, for the reply specifications.
t
addr:
PP,
MM -- search
Search backwards starting at address addr for a match with pattern
PP and mask MM. PP and MM are 4 bytes.
addr must be at least 3 digits.
T
XX -- thread alive
Find out if the thread XX is alive.
Reply:
OK
E
NN
u
-- reserved
U
-- reserved
v
-- reserved
V
-- reserved
w
-- reserved
W
-- reserved
x
-- reserved
X
addr,
length:XX... -- write mem (binary)
addr is address, length is number of bytes, XX...
is binary data. The characters $
, #
, and 0x7d
are
escaped using 0x7d
.
Reply:
OK
E
NN
y
-- reserved
Y
reserved
z
t,
addr,
length -- remove break or watchpoint (draft)
Z
t,
addr,
length -- insert break or watchpoint (draft)
t is type: 0
- software breakpoint, 1
- hardware
breakpoint, 2
-- write watchpoint, 3
- read watchpoint,
4
- access watchpoint; addr is address; length is in
bytes. For a software breakpoint, length specifies the size of
the instruction to be patched. For hardware breakpoints and watchpoints
length specifies the memory region to be monitored. To avoid
potential problems with duplicate packets, the operations should be
implemented in an idempotent way.
Reply:
E
NN
OK