From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4164 invoked by alias); 15 Aug 2002 23:18:59 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 4041 invoked from network); 15 Aug 2002 23:18:57 -0000 Received: from unknown (HELO localhost.redhat.com) (216.138.202.10) by sources.redhat.com with SMTP; 15 Aug 2002 23:18:57 -0000 Received: from ges.redhat.com (localhost [127.0.0.1]) by localhost.redhat.com (Postfix) with ESMTP id B4B663C03; Thu, 15 Aug 2002 19:18:55 -0400 (EDT) Message-ID: <3D5C36DF.6010403@ges.redhat.com> Date: Thu, 15 Aug 2002 16:18:00 -0000 From: Andrew Cagney User-Agent: Mozilla/5.0 (X11; U; NetBSD macppc; en-US; rv:1.0.0) Gecko/20020810 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Eli Zaretskii Cc: gdb-patches@sources.redhat.com Subject: Re: [patch/rfa:doco] Reformat ``Remote Protocol'' appendix References: <3D4D6494.30807@ges.redhat.com> <2950-Tue13Aug2002133142+0300-eliz@is.elta.co.il> <3D59A180.4090403@ges.redhat.com> <3405-Wed14Aug2002135202+0300-eliz@is.elta.co.il> <3D5A7AA4.9080702@ges.redhat.com> <9003-Thu15Aug2002194921+0300-eliz@is.elta.co.il> Content-Type: multipart/mixed; boundary="------------060902010609060508030203" X-SW-Source: 2002-08/txt/msg00393.txt.bz2 This is a multi-part message in MIME format. --------------060902010609060508030203 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Content-length: 70 Ok, how's the attached? It contains some more index entries. Andrew --------------060902010609060508030203 Content-Type: text/plain; name="gdb.texinfo" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="gdb.texinfo" Content-length: 25985 @node Remote Protocol @appendix @value{GDBN} Remote Serial Protocol @menu * Overview:: * Packets:: * Stop Reply Packets:: * General Query Packets:: * Register Packet Format:: * Examples:: @end menu @node Overview @section Overview There may be occasions when you need to know something about the protocol---for example, if there is only one serial port to your target machine, you might want your program to do something special if it recognizes a packet meant for @value{GDBN}. In the examples below, @samp{<-} and @samp{->} are used to indicate transmitted and received data respectfully. @cindex protocol, @value{GDBN} remote serial @cindex serial protocol, @value{GDBN} remote @cindex remote serial protocol All @value{GDBN} commands and responses (other than acknowledgments) are sent as a @var{packet}. A @var{packet} is introduced with the character @samp{$}, the actual @var{packet-data}, and the terminating character @samp{#} followed by a two-digit @var{checksum}: @smallexample @code{$}@var{packet-data}@code{#}@var{checksum} @end smallexample @noindent @cindex checksum, for @value{GDBN} remote @noindent The two-digit @var{checksum} is computed as the modulo 256 sum of all characters between the leading @samp{$} and the trailing @samp{#} (an eight bit unsigned checksum). Implementors should note that prior to @value{GDBN} 5.0 the protocol specification also included an optional two-digit @var{sequence-id}: @smallexample @code{$}@var{sequence-id}@code{:}@var{packet-data}@code{#}@var{checksum} @end smallexample @cindex sequence-id, for @value{GDBN} remote @noindent That @var{sequence-id} was appended to the acknowledgment. @value{GDBN} has never output @var{sequence-id}s. Stubs that handle packets added since @value{GDBN} 5.0 must not accept @var{sequence-id}. @cindex acknowledgment, for @value{GDBN} remote When either the host or the target machine receives a packet, the first response expected is an acknowledgment: either @samp{+} (to indicate the package was received correctly) or @samp{-} (to request retransmission): @smallexample <- @code{$}@var{packet-data}@code{#}@var{checksum} -> @code{+} @end smallexample @noindent The host (@value{GDBN}) sends @var{command}s, and the target (the debugging stub incorporated in your program) sends a @var{response}. In the case of step and continue @var{command}s, the response is only sent when the operation has completed (the target has again stopped). @var{packet-data} consists of a sequence of characters with the exception of @samp{#} and @samp{$} (see @samp{X} packet for additional exceptions). Fields within the packet should be separated using @samp{,} @samp{;} or @cindex remote protocol, field separator @samp{:}. Except where otherwise noted all numbers are represented in @sc{hex} with leading zeros suppressed. Implementors should note that prior to @value{GDBN} 5.0, the character @samp{:} could not appear as the third character in a packet (as it would potentially conflict with the @var{sequence-id}). Response @var{data} can be run-length encoded to save space. A @samp{*} means that the next character is an @sc{ascii} encoding giving a repeat count which stands for that many repetitions of the character preceding the @samp{*}. The encoding is @code{n+29}, yielding a printable character where @code{n >=3} (which is where rle starts to win). The printable characters @samp{$}, @samp{#}, @samp{+} and @samp{-} or with a numeric value greater than 126 should not be used. Some remote systems have used a different run-length encoding mechanism loosely refered to as the cisco encoding. Following the @samp{*} character are two hex digits that indicate the size of the packet. So: @smallexample "@code{0* }" @end smallexample @noindent means the same as "0000". The error response returned for some packets includes a two character error number. That number is not well defined. For any @var{command} not supported by the stub, an empty response (@samp{$#00}) should be returned. That way it is possible to extend the protocol. A newer @value{GDBN} can tell if a packet is supported based on that response. A stub is required to support the @samp{g}, @samp{G}, @samp{m}, @samp{M}, @samp{c}, and @samp{s} @var{command}s. All other @var{command}s are optional. @node Packets @section Packets The following table provides a complete list of all currently defined @var{command}s and their corresponding response @var{data}. @table @r @item @code{!} --- extended mode @cindex @code{!} packet Enable extended mode. In extended mode, the remote server is made persistent. The @samp{R} packet is used to restart the program being debugged. Reply: @table @samp @item OK The remote target both supports and has enabled extended mode. @end table @item @code{?} --- last signal @cindex @code{?} packet Indicate the reason the target halted. The reply is the same as for step and continue. Reply: @xref{Stop Reply Packets}, for the reply specifications. @item @code{a} --- reserved Reserved for future use. @item @code{A}@var{arglen}@code{,}@var{argnum}@code{,}@var{arg}@code{,@dots{}} --- set program arguments @strong{(reserved)} @cindex @code{A} packet Initialized @samp{argv[]} array passed into program. @var{arglen} specifies the number of bytes in the hex encoded byte stream @var{arg}. See @code{gdbserver} for more details. Reply: @table @samp @item OK @item E@var{NN} @end table @item @code{b}@var{baud} --- set baud @strong{(deprecated)} @cindex @code{b} packet Change the serial line speed to @var{baud}. JTC: @emph{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: @emph{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.} @item @code{B}@var{addr},@var{mode} --- set breakpoint @strong{(deprecated)} @cindex @code{B} packet Set (@var{mode} is @samp{S}) or clear (@var{mode} is @samp{C}) a breakpoint at @var{addr}. @emph{This has been replaced by the @samp{Z} and @samp{z} packets.} @item @code{c}@var{addr} --- continue @cindex @code{c} packet @var{addr} is address to resume. If @var{addr} is omitted, resume at current address. Reply: @xref{Stop Reply Packets}, for the reply specifications. @item @code{C}@var{sig}@code{;}@var{addr} --- continue with signal @cindex @code{C} packet Continue with signal @var{sig} (hex signal number). If @code{;}@var{addr} is omitted, resume at same address. Reply: @xref{Stop Reply Packets}, for the reply specifications. @item @code{d} --- toggle debug @strong{(deprecated)} @cindex @code{d} packet Toggle debug flag. @item @code{D} --- detach @cindex @code{D} packet Detach @value{GDBN} from the remote system. Sent to the remote target before @value{GDBN} disconnects. Reply: @table @samp @item @emph{no response} @value{GDBN} does not check for any response after sending this packet. @end table @item @code{e} --- reserved Reserved for future use. @item @code{E} --- reserved Reserved for future use. @item @code{f} --- reserved Reserved for future use. @item @code{F} --- reserved Reserved for future use. @item @code{g} --- read registers @anchor{read registers packet} @cindex @code{g} packet Read general registers. Reply: @table @samp @item @var{XX@dots{}} Each byte of register data is described by two hex digits. The bytes with the register are transmitted in target byte order. The size of each register and their position within the @samp{g} @var{packet} are determined by the @value{GDBN} internal macros @var{REGISTER_RAW_SIZE} and @var{REGISTER_NAME} macros. The specification of several standard @code{g} packets is specified below. @item E@var{NN} for an error. @end table @item @code{G}@var{XX@dots{}} --- write regs @cindex @code{G} packet @xref{read registers packet}, for a description of the @var{XX@dots{}} data. Reply: @table @samp @item OK for success @item E@var{NN} for an error @end table @item @code{h} --- reserved Reserved for future use. @item @code{H}@var{c}@var{t@dots{}} --- set thread @cindex @code{H} packet Set thread for subsequent operations (@samp{m}, @samp{M}, @samp{g}, @samp{G}, et.al.). @var{c} depends on the operation to be performed: it should be @samp{c} for step and continue operations, @samp{g} for other operations. The thread designator @var{t@dots{}} may be -1, meaning all the threads, a thread number, or zero which means pick any thread. Reply: @table @samp @item OK for success @item E@var{NN} for an error @end table @c FIXME: JTC: @c 'H': How restrictive (or permissive) is the thread model. If a @c thread is selected and stopped, are other threads allowed @c to continue to execute? As I mentioned above, I think the @c semantics of each command when a thread is selected must be @c described. For example: @c @c 'g': If the stub supports threads and a specific thread is @c selected, returns the register block from that thread; @c otherwise returns current registers. @c @c 'G' If the stub supports threads and a specific thread is @c selected, sets the registers of the register block of @c that thread; otherwise sets current registers. @item @code{i}@var{addr}@code{,}@var{nnn} --- cycle step @strong{(draft)} @anchor{cycle step packet} @cindex @code{i} packet Step the remote target by a single clock cycle. If @code{,}@var{nnn} is present, cycle step @var{nnn} cycles. If @var{addr} is present, cycle step starting at that address. @item @code{I} --- signal then cycle step @strong{(reserved)} @cindex @code{I} packet @xref{step with signal packet}. @xref{cycle step packet}. @item @code{j} --- reserved Reserved for future use. @item @code{J} --- reserved Reserved for future use. @item @code{k} --- kill request @cindex @code{k} packet FIXME: @emph{There is no description of how to operate when a specific thread context has been selected (i.e.@: does 'k' kill only that thread?)}. @item @code{K} --- reserved Reserved for future use. @item @code{l} --- reserved Reserved for future use. @item @code{L} --- reserved Reserved for future use. @item @code{m}@var{addr}@code{,}@var{length} --- read memory @cindex @code{m} packet Read @var{length} bytes of memory starting at address @var{addr}. Neither @value{GDBN} nor the stub assume that sized memory transfers are assumed using word alligned accesses. FIXME: @emph{A word aligned memory transfer mechanism is needed.} Reply: @table @samp @item @var{XX@dots{}} @var{XX@dots{}} is mem contents. Can be fewer bytes than requested if able to read only part of the data. Neither @value{GDBN} nor the stub assume that sized memory transfers are assumed using word alligned accesses. FIXME: @emph{A word aligned memory transfer mechanism is needed.} @item E@var{NN} @var{NN} is errno @end table @item @code{M}@var{addr},@var{length}@code{:}@var{XX@dots{}} --- write mem @cindex @code{M} packet Write @var{length} bytes of memory starting at address @var{addr}. @var{XX@dots{}} is the data. Reply: @table @samp @item OK for success @item E@var{NN} for an error (this includes the case where only part of the data was written). @end table @item @code{n} --- reserved Reserved for future use. @item @code{N} --- reserved Reserved for future use. @item @code{o} --- reserved Reserved for future use. @item @code{O} --- reserved Reserved for future use. @item @code{p}@var{n@dots{}} --- read reg @strong{(reserved)} @cindex @code{p} packet @xref{write register packet}. Reply: @table @samp @item @var{r@dots{}.} The hex encoded value of the register in target byte order. @end table @item @code{P}@var{n@dots{}}@code{=}@var{r@dots{}} --- write register @anchor{write register packet} @cindex @code{P} packet Write register @var{n@dots{}} with value @var{r@dots{}}, which contains two hex digits for each byte in the register (target byte order). Reply: @table @samp @item OK for success @item E@var{NN} for an error @end table @item @code{q}@var{query} --- general query @anchor{general query packet} @cindex @code{q} packet Request info about @var{query}. In general @value{GDBN} queries have a leading upper case letter. Custom vendor queries should use a company prefix (in lower case) ex: @samp{qfsf.var}. @var{query} may optionally be followed by a @samp{,} or @samp{;} separated list. Stubs must ensure that they match the full @var{query} name. Reply: @table @samp @item @var{XX@dots{}} Hex encoded data from query. The reply can not be empty. @item E@var{NN} error reply @item Indicating an unrecognized @var{query}. @end table @item @code{Q}@var{var}@code{=}@var{val} --- general set @cindex @code{Q} packet Set value of @var{var} to @var{val}. @xref{general query packet}, for a discussion of naming conventions. @item @code{r} --- reset @strong{(deprecated)} @cindex @code{r} packet Reset the entire system. @item @code{R}@var{XX} --- remote restart @cindex @code{R} packet Restart the program being debugged. @var{XX}, while needed, is ignored. This packet is only available in extended mode. Reply: @table @samp @item @emph{no reply} The @samp{R} packet has no reply. @end table @item @code{s}@var{addr} --- step @cindex @code{s} packet @var{addr} is address to resume. If @var{addr} is omitted, resume at same address. Reply: @xref{Stop Reply Packets}, for the reply specifications. @item @code{S}@var{sig}@code{;}@var{addr} --- step with signal @anchor{step with signal packet} @cindex @code{S} packet Like @samp{C} but step not continue. Reply: @xref{Stop Reply Packets}, for the reply specifications. @item @code{t}@var{addr}@code{:}@var{PP}@code{,}@var{MM} --- search @cindex @code{t} packet Search backwards starting at address @var{addr} for a match with pattern @var{PP} and mask @var{MM}. @var{PP} and @var{MM} are 4 bytes. @var{addr} must be at least 3 digits. @item @code{T}@var{XX} --- thread alive @cindex @code{T} packet Find out if the thread XX is alive. Reply: @table @samp @item OK thread is still alive @item E@var{NN} thread is dead @end table @item @code{u} --- reserved Reserved for future use. @item @code{U} --- reserved Reserved for future use. @item @code{v} --- reserved Reserved for future use. @item @code{V} --- reserved Reserved for future use. @item @code{w} --- reserved Reserved for future use. @item @code{W} --- reserved Reserved for future use. @item @code{x} --- reserved Reserved for future use. @item @code{X}@var{addr}@code{,}@var{length}@var{:}@var{XX@dots{}} --- write mem (binary) @cindex @code{X} packet @var{addr} is address, @var{length} is number of bytes, @var{XX@dots{}} is binary data. The characters @code{$}, @code{#}, and @code{0x7d} are escaped using @code{0x7d}. Reply: @table @samp @item OK for success @item E@var{NN} for an error @end table @item @code{y} --- reserved Reserved for future use. @item @code{Y} reserved Reserved for future use. @item @code{z}@var{t}@code{,}@var{addr}@code{,}@var{length} --- remove break or watchpoint @strong{(draft)} @cindex @code{z} packet @xref{insert breakpoint or watchpoint packet}. @item @code{Z}@var{t}@code{,}@var{addr}@code{,}@var{length} --- insert break or watchpoint @strong{(draft)} @anchor{insert breakpoint or watchpoint packet} @cindex @code{Z} packet @var{t} is type: @samp{0} - software breakpoint, @samp{1} - hardware breakpoint, @samp{2} --- write watchpoint, @samp{3} - read watchpoint, @samp{4} - access watchpoint; @var{addr} is address; @var{length} is in bytes. For a software breakpoint, @var{length} specifies the size of the instruction to be patched. For hardware breakpoints and watchpoints @var{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: @table @samp @item E@var{NN} for an error @item OK for success @item @samp{} If not supported. @end table @end table @node Stop Reply Packets @section Stop Reply Packets @cindex stop reply packets The @samp{C}, @samp{c}, @samp{S}, @samp{s} and @samp{?} packets can receive any of the below as a reply. In the case of the @samp{C}, @samp{c}, @samp{S} and @samp{s} packets, that reply is only returned when the target halts. In the below the exact meaning of @samp{signal number} is poorly defined. In general one of the UNIX signal numbering conventions is used. @table @samp @item S@var{AA} @var{AA} is the signal number @item @code{T}@var{AA}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;} @cindex @code{T} packet reply @var{AA} = two hex digit signal number; @var{n...} = register number (hex), @var{r...} = target byte ordered register contents, size defined by @code{REGISTER_RAW_SIZE}; @var{n...} = @samp{thread}, @var{r...} = thread process ID, this is a hex integer; @var{n...} = (@samp{watch} | @samp{rwatch} | @samp{awatch}, @var{r...} = data address, this is a hex integer; @var{n...} = other string not starting with valid hex digit. @value{GDBN} should ignore this @var{n...}, @var{r...} pair and go on to the next. This way we can extend the protocol. @item W@var{AA} The process exited, and @var{AA} is the exit status. This is only applicable to certain targets. @item X@var{AA} The process terminated with signal @var{AA}. @item N@var{AA};@var{t@dots{}};@var{d@dots{}};@var{b@dots{}} @strong{(obsolete)} @var{AA} = signal number; @var{t@dots{}} = address of symbol @code{_start}; @var{d@dots{}} = base of data section; @var{b@dots{}} = base of bss section. @emph{Note: only used by Cisco Systems targets. The difference between this reply and the @samp{qOffsets} query is that the @samp{N} packet may arrive spontaneously whereas the @samp{qOffsets} is a query initiated by the host debugger.} @item O@var{XX@dots{}} @var{XX@dots{}} is hex encoding of @sc{ascii} data. This can happen at any time while the program is running and the debugger should continue to wait for @samp{W}, @samp{T}, etc. @end table @node General Query Packets @section General Query Packets The following set and query packets have already been defined. @table @r @item @code{q}@code{C} --- current thread Return the current thread id. Reply: @table @samp @item @code{QC}@var{pid} Where @var{pid} is a HEX encoded 16 bit process id. @item * Any other reply implies the old pid. @end table @item @code{q}@code{fThreadInfo} -- all thread ids @code{q}@code{sThreadInfo} Obtain a list of active thread ids from the target (OS). Since there may be too many active threads to fit into one reply packet, this query works iteratively: it may require more than one query/reply sequence to obtain the entire list of threads. The first query of the sequence will be the @code{qf}@code{ThreadInfo} query; subsequent queries in the sequence will be the @code{qs}@code{ThreadInfo} query. NOTE: replaces the @code{qL} query (see below). Reply: @table @samp @item @code{m}@var{id} A single thread id @item @code{m}@var{id},@var{id}@dots{} a comma-separated list of thread ids @item @code{l} (lower case 'el') denotes end of list. @end table In response to each query, the target will reply with a list of one or more thread ids, in big-endian hex, separated by commas. @value{GDBN} will respond to each reply with a request for more thread ids (using the @code{qs} form of the query), until the target responds with @code{l} (lower-case el, for @code{'last'}). @item @code{q}@code{ThreadExtraInfo}@code{,}@var{id} --- extra thread info Where @var{id} is a thread-id in big-endian hex. Obtain a printable string description of a thread's attributes from the target OS. This string may contain anything that the target OS thinks is interesting for @value{GDBN} to tell the user about the thread. The string is displayed in @value{GDBN}'s @samp{info threads} display. Some examples of possible thread extra info strings are ``Runnable'', or ``Blocked on Mutex''. Reply: @table @samp @item @var{XX@dots{}} Where @var{XX@dots{}} is a hex encoding of @sc{ascii} data, comprising the printable string containing the extra information about the thread's attributes. @end table @item @code{q}@code{L}@var{startflag}@var{threadcount}@var{nextthread} --- query @var{LIST} or @var{threadLIST} @strong{(deprecated)} Obtain thread information from RTOS. Where: @var{startflag} (one hex digit) is one to indicate the first query and zero to indicate a subsequent query; @var{threadcount} (two hex digits) is the maximum number of threads the response packet can contain; and @var{nextthread} (eight hex digits), for subsequent queries (@var{startflag} is zero), is returned in the response as @var{argthread}. NOTE: this query is replaced by the @code{q}@code{fThreadInfo} query (see above). Reply: @table @samp @item @code{q}@code{M}@var{count}@var{done}@var{argthread}@var{thread@dots{}} Where: @var{count} (two hex digits) is the number of threads being returned; @var{done} (one hex digit) is zero to indicate more threads and one indicates no further threads; @var{argthreadid} (eight hex digits) is @var{nextthread} from the request packet; @var{thread@dots{}} is a sequence of thread IDs from the target. @var{threadid} (eight hex digits). See @code{remote.c:parse_threadlist_response()}. @end table @item @code{q}@code{CRC:}@var{addr}@code{,}@var{length} --- compute CRC of memory block Reply: @table @samp @item @code{E}@var{NN} An error (such as memory fault) @item @code{C}@var{CRC32} A 32 bit cyclic redundancy check of the specified memory region. @end table @item @code{q}@code{Offsets} --- query sect offs Get section offsets that the target used when re-locating the downloaded image. @emph{Note: while a @code{Bss} offset is included in the response, @value{GDBN} ignores this and instead applies the @code{Data} offset to the @code{Bss} section.} Reply: @table @samp @item @code{Text=}@var{xxx}@code{;Data=}@var{yyy}@code{;Bss=}@var{zzz} @end table @item @code{q}@code{P}@var{mode}@var{threadid} --- thread info request Returns information on @var{threadid}. Where: @var{mode} is a hex encoded 32 bit mode; @var{threadid} is a hex encoded 64 bit thread ID. Reply: @table @samp @item * @end table See @code{remote.c:remote_unpack_thread_info_response()}. @item @code{q}@code{Rcmd,}@var{command} --- remote command @var{command} (hex encoded) is passed to the local interpreter for execution. Invalid commands should be reported using the output string. Before the final result packet, the target may also respond with a number of intermediate @code{O}@var{output} console output packets. @emph{Implementors should note that providing access to a stubs's interpreter may have security implications}. Reply: @table @samp @item OK A command response with no output. @item @var{OUTPUT} A command response with the hex encoded output string @var{OUTPUT}. @item @code{E}@var{NN} Indicate a badly formed request. @item @samp{} When @samp{q}@samp{Rcmd} is not recognized. @end table @item @code{qSymbol::} --- symbol lookup Notify the target that @value{GDBN} is prepared to serve symbol lookup requests. Accept requests from the target for the values of symbols. Reply: @table @samp @item @code{OK} The target does not need to look up any (more) symbols. @item @code{qSymbol:}@var{sym_name} The target requests the value of symbol @var{sym_name} (hex encoded). @value{GDBN} may provide the value by using the @code{qSymbol:}@var{sym_value}:@var{sym_name} message, described below. @end table @item @code{qSymbol:}@var{sym_value}:@var{sym_name} --- symbol value Set the value of @var{sym_name} to @var{sym_value}. @var{sym_name} (hex encoded) is the name of a symbol whose value the target has previously requested. @var{sym_value} (hex) is the value for symbol @var{sym_name}. If @value{GDBN} cannot supply a value for @var{sym_name}, then this field will be empty. Reply: @table @samp @item @code{OK} The target does not need to look up any (more) symbols. @item @code{qSymbol:}@var{sym_name} The target requests the value of a new symbol @var{sym_name} (hex encoded). @value{GDBN} will continue to supply the values of symbols (if available), until the target ceases to request them. @end table @end table @node Register Packet Format @section Register Packet Format The following @samp{g}/@samp{G} packets have previously been defined. In the below, some thirty-two bit registers are transferred as sixty-four bits. Those registers should be zero/sign extended (which?) to fill the space allocated. Register bytes are transfered in target byte order. The two nibbles within a register byte are transfered most-significant - least-significant. @table @r @item MIPS32 All registers are transfered as thirty-two bit quantities in the order: 32 general-purpose; sr; lo; hi; bad; cause; pc; 32 floating-point registers; fsr; fir; fp. @item MIPS64 All registers are transfered as sixty-four bit quantities (including thirty-two bit registers such as @code{sr}). The ordering is the same as @code{MIPS32}. @end table @node Examples @section Examples Example sequence of a target being re-started. Notice how the restart does not get any direct output: @smallexample <- @code{R00} -> @code{+} @emph{target restarts} <- @code{?} -> @code{+} -> @code{T001:1234123412341234} <- @code{+} @end smallexample Example sequence of a target being stepped by a single instruction: @smallexample <- @code{G1445@dots{}} -> @code{+} <- @code{s} -> @code{+} @emph{time passes} -> @code{T001:1234123412341234} <- @code{+} <- @code{g} -> @code{+} -> @code{1455@dots{}} <- @code{+} @end smallexample --------------060902010609060508030203--