From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5049 invoked by alias); 23 Dec 2010 19:13:19 -0000 Received: (qmail 5040 invoked by uid 22791); 23 Dec 2010 19:13:18 -0000 X-SWARE-Spam-Status: No, hits=-1.9 required=5.0 tests=AWL,BAYES_00,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mail.codesourcery.com (HELO mail.codesourcery.com) (38.113.113.100) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 23 Dec 2010 19:13:13 +0000 Received: (qmail 19164 invoked from network); 23 Dec 2010 19:13:11 -0000 Received: from unknown (HELO orlando.localnet) (pedro@127.0.0.2) by mail.codesourcery.com with ESMTPA; 23 Dec 2010 19:13:11 -0000 From: Pedro Alves To: gdb-patches@sourceware.org Subject: [doc] Remote protocol: undocumented return value for 'p' and 'g' Date: Thu, 23 Dec 2010 19:52:00 -0000 User-Agent: KMail/1.13.5 (Linux/2.6.33-29-realtime; KDE/4.4.5; x86_64; ; ) MIME-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Message-Id: <201012231913.08466.pedro@codesourcery.com> X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2010-12/txt/msg00442.txt.bz2 Ref: The feature this documents was added back here: Thu Oct 29 10:04:20 1998 Michael Snyder [Support for trace debugging: registers that were not collected.] * remote.c (remote_fetch_registers): accept 'xxxx' in the register packet, with the meaning "register value is not available". Set register_valid to -1, which will connote "no value available". * findvar.c (read_relative_register_raw_bytes): return failure if register_valid == -1. (value_of_register): return failure if register_valid == -1. (read_var_value): return error if value_of_register fails for a register variable. (value_from_register): return failure if register_valid == -1. * eval.c (evaluate_subexp_standard): return error if value_of_register fails for a register used in an expression. * infcmd.c (do_registers_info): display "value not available" for registers for which register_valid == -1. * tracepoint.c (set_raw_tracepoint): just save the filename as is from the symbol table, rather than trying to prepend the dir name. Also save the bfd section. (tracepoints_info): use the section when looking up the function name. * tracepoint.h: add section field to tracepoint struct. It's intended usage is in the context of inspecting tracepoints, to report "the register exists, but I don't know its value, because I haven't collected it." (We actually have a local series of 60 or so (and counting) trace debugging related patches that actually make use of this mechanism). Okay to apply? -- Pedro Alves 2010-12-23 Pedro Alves gdb/doc/ * gdb.texinfo (Packets) : Document support for registers that were not collected. --- gdb/doc/gdb.texinfo | 15 +++++++++++++++ 1 file changed, 15 insertions(+) Index: src/gdb/doc/gdb.texinfo =================================================================== --- src.orig/gdb/doc/gdb.texinfo 2010-12-13 16:31:07.000000000 +0000 +++ src/gdb/doc/gdb.texinfo 2010-12-23 18:43:29.000000000 +0000 @@ -31796,6 +31796,21 @@ each register and their position within determined by the @value{GDBN} internal gdbarch functions @code{DEPRECATED_REGISTER_RAW_SIZE} and @code{gdbarch_register_name}. The specification of several standard @samp{g} packets is specified below. + +When reading registers from a trace frame (@pxref{Analyze Collected +Data,,Using the Collected Data}), the stub may also return a string of +literal @samp{x}'s in place of the register data digits, to indicate +the corresponding register has not been collected, thus its value is +unavailable. For example, for an architecture with 4 registers of 4 +bytes each, the following reply indicates to @value{GDBN} that +registers 0 and 2 have not been collected, while registers 1 and 3 +have been collected, and have value zero each: + +@smallexample +-> @code{g} +<- @code{xxxxxxxx00000000xxxxxxxx00000000} +@end smallexample + @item E @var{NN} for an error. @end table