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(Set Watchpoints): Document can-use-hw-watchpoints.

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Rearrange index entries and improve wording about support for
hardware watchpoints.
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Eli Zaretskii 2005-04-02 08:32:31 +00:00
parent 0c98cc2b81
commit 82f2d80296
2 changed files with 22 additions and 7 deletions
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6
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@ -1,3 +1,9 @@
2005-04-01 Eli Zaretskii <eliz@gnu.org>
* gdb.texinfo (Set Watchpoints): Document can-use-hw-watchpoints.
Rearrange index entries and improve wording about support for
hardware watchpoints.
2005-03-10 Bob Rossi <bob@brasko.net>
* gdb.texinfo: Update copyright

23
gdb/doc/gdb.texinfo
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@ -2741,12 +2741,12 @@ You can see these breakpoints with the @value{GDBN} maintenance command
@subsection Setting watchpoints
@cindex setting watchpoints
@cindex software watchpoints
@cindex hardware watchpoints
You can use a watchpoint to stop execution whenever the value of an
expression changes, without having to predict a particular place where
this may happen.
@cindex software watchpoints
@cindex hardware watchpoints
Depending on your system, watchpoints may be implemented in software or
hardware. @value{GDBN} does software watchpointing by single-stepping your
program and testing the variable's value each time, which is hundreds of
@ -2754,10 +2754,9 @@ times slower than normal execution. (But this may still be worth it, to
catch errors where you have no clue what part of your program is the
culprit.)
On some systems, such as HP-UX, @sc{gnu}/Linux and some other x86-based targets,
@value{GDBN} includes support for
hardware watchpoints, which do not slow down the running of your
program.
On some systems, such as HP-UX, @sc{gnu}/Linux and most other
x86-based targets, @value{GDBN} includes support for hardware
watchpoints, which do not slow down the running of your program.
@table @code
@kindex watch
@ -2785,7 +2784,17 @@ watchpoints execute very quickly, and the debugger reports a change in
value at the exact instruction where the change occurs. If @value{GDBN}
cannot set a hardware watchpoint, it sets a software watchpoint, which
executes more slowly and reports the change in value at the next
statement, not the instruction, after the change occurs.
@emph{statement}, not the instruction, after the change occurs.
@vindex can-use-hw-watchpoints
@cindex use only software watchpoints
You can force @value{GDBN} to use only software watchpoints with the
@kbd{set can-use-hw-watchpoints 0} command. With this variable set to
zero, @value{GDBN} will never try to use hardware watchpoints, even if
the underlying system supports them. (Note that hardware-assisted
watchpoints that were set @emph{before} setting
@code{can-use-hw-watchpoints} to zero will still use the hardware
mechanism of watching expressiion values.)
When you issue the @code{watch} command, @value{GDBN} reports