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Documentation for DTrace USDT probes. 

This patch modifies the `Static Probe Points' section on the GDB
manual in order to cover the support for DTrace USDT probes, in
addition to SystemTap SDT probes.

gdb/doc/ChangeLog:

2015-02-17  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* gdb.texinfo (Static Probe Points): Add cindex `static probe
	point, DTrace'.
	(Static Probe Points): Modified to cover DTrace probes in addition
	to SystemTap probes.  Also modified to cover the `enable probe'
	and `disable probe' commands.
This commit is contained in:
Jose E. Marchesi 2015-02-17 16:42:15 +01:00
parent 497c491bea
commit 3133f8c11f
2 changed files with 47 additions and 19 deletions
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8
gdb/doc/ChangeLog
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@ -1,3 +1,11 @@
2015-02-17 Jose E. Marchesi <jose.marchesi@oracle.com>
* gdb.texinfo (Static Probe Points): Add cindex `static probe
point, DTrace'.
(Static Probe Points): Modified to cover DTrace probes in addition
to SystemTap probes. Also modified to cover the `enable probe'
and `disable probe' commands.
2015-02-17 Jose E. Marchesi <jose.marchesi@oracle.com>
* gdb.texinfo (Static Probe Points): Cover the `enable probe' and

58
gdb/doc/gdb.texinfo
View File

@ -4967,34 +4967,50 @@ that can no longer be recreated.
@subsection Static Probe Points
@cindex static probe point, SystemTap
@cindex static probe point, DTrace
@value{GDBN} supports @dfn{SDT} probes in the code. @acronym{SDT} stands
for Statically Defined Tracing, and the probes are designed to have a tiny
runtime code and data footprint, and no dynamic relocations. They are
usable from assembly, C and C@t{++} languages. See
@uref{http://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation}
for a good reference on how the @acronym{SDT} probes are implemented.
runtime code and data footprint, and no dynamic relocations.
Currently, @code{SystemTap} (@uref{http://sourceware.org/systemtap/})
@acronym{SDT} probes are supported on ELF-compatible systems. See
Currently, the following types of probes are supported on
ELF-compatible systems:
@itemize @bullet
@item @code{SystemTap} (@uref{http://sourceware.org/systemtap/})
@acronym{SDT} probes@footnote{See
@uref{http://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps}
for more information on how to add @code{SystemTap} @acronym{SDT} probes
in your applications.
for more information on how to add @code{SystemTap} @acronym{SDT}
probes in your applications.}. @code{SystemTap} probes are usable
from assembly, C and C@t{++} languages@footnote{See
@uref{http://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation}
for a good reference on how the @acronym{SDT} probes are implemented.}.
@item @code{DTrace} (@uref{http://oss.oracle.com/projects/DTrace})
@acronym{USDT} probes. @code{DTrace} probes are usable from C and
C@t{++} languages.
@end itemize
@cindex semaphores on static probe points
Some probes have an associated semaphore variable; for instance, this
happens automatically if you defined your probe using a DTrace-style
@file{.d} file. If your probe has a semaphore, @value{GDBN} will
automatically enable it when you specify a breakpoint using the
@samp{-probe-stap} notation. But, if you put a breakpoint at a probe's
location by some other method (e.g., @code{break file:line}), then
@value{GDBN} will not automatically set the semaphore.
Some @code{SystemTap} probes have an associated semaphore variable;
for instance, this happens automatically if you defined your probe
using a DTrace-style @file{.d} file. If your probe has a semaphore,
@value{GDBN} will automatically enable it when you specify a
breakpoint using the @samp{-probe-stap} notation. But, if you put a
breakpoint at a probe's location by some other method (e.g.,
@code{break file:line}), then @value{GDBN} will not automatically set
the semaphore. @code{DTrace} probes do not support semaphores.
You can examine the available static static probes using @code{info
probes}, with optional arguments:
@table @code
@kindex info probes
@item info probes stap @r{[}@var{provider} @r{[}@var{name} @r{[}@var{objfile}@r{]}@r{]}@r{]}
@item info probes @r{[}@var{type}@r{]} @r{[}@var{provider} @r{[}@var{name} @r{[}@var{objfile}@r{]}@r{]}@r{]}
If given, @var{type} is either @code{stap} for listing
@code{SystemTap} probes or @code{dtrace} for listing @code{DTrace}
probes. If omitted all probes are listed regardless of their types.
If given, @var{provider} is a regular expression used to match against provider
names when selecting which probes to list. If omitted, probes by all
probes from all providers are listed.
@ -5014,7 +5030,8 @@ List the available static probes, from all types.
@cindex enabling and disabling probes
Some probe points can be enabled and/or disabled. The effect of
enabling or disabling a probe depends on the type of probe being
handled. @code{SystemTap} probes cannot be disabled.
handled. Some @code{DTrace} probes can be enabled or
disabled, but @code{SystemTap} probes cannot be disabled.
You can enable (or disable) one or more probes using the following
commands, with optional arguments:
@ -5045,8 +5062,11 @@ A probe may specify up to twelve arguments. These are available at the
point at which the probe is defined---that is, when the current PC is
at the probe's location. The arguments are available using the
convenience variables (@pxref{Convenience Vars})
@code{$_probe_arg0}@dots{}@code{$_probe_arg11}. Each probe argument is
an integer of the appropriate size; types are not preserved. The
@code{$_probe_arg0}@dots{}@code{$_probe_arg11}. In @code{SystemTap}
probes each probe argument is an integer of the appropriate size;
types are not preserved. In @code{DTrace} probes types are preserved
provided that they are recognized as such by @value{GDBN}; otherwise
the value of the probe argument will be a long integer. The
convenience variable @code{$_probe_argc} holds the number of arguments
at the current probe point.