Corrupted data ending in a crash Non-deterministic behavior Solution is to synchronize concurrent accesses, e. Thread-level ordering global synchronization Note: Race free but still not necessarily run-to-run reproducible results! Not all of them might incur data races.
Address Where the breakpoint is in your program, as a memory address. See below for details. What Where the breakpoint is in the source for your program, as a file and line number.
For a pending breakpoint, the original string passed to the breakpoint command will be listed as it cannot be resolved until the appropriate shared library is loaded in the future. If a breakpoint is conditional, there are two evaluation modes: The info break command shows the condition on the line following the affected breakpoint, together with its condition evaluation mode in between parentheses.
Breakpoint commands, if any, are listed after that. A pending breakpoint is allowed to have a condition specified for it.
The condition is not parsed for validity until a shared library is loaded that allows the pending breakpoint to resolve to a valid location. This is especially useful in conjunction with the ignore command. You can ignore a large number of breakpoint hits, look at the breakpoint info to see how many times the breakpoint was hit, and then run again, ignoring one less than that number.
This will get you quickly to the last hit of that breakpoint. For a breakpoints with an enable count xref greater than 1, info break also displays that count.
GDB allows you to set any number of breakpoints at the same place in your program. There is nothing silly or meaningless about this. When the breakpoints are conditional, this is even useful see Break Conditions.
It is possible that a breakpoint corresponds to several locations in your program. Examples of this situation are: Multiple functions in the program may have the same name.
For an inlined function, a given source line can correspond to several places where that function is inlined. In all those cases, GDB will insert a breakpoint at all the relevant locations.
A breakpoint with multiple locations is displayed in the breakpoint table using several rows—one header row, followed by one row for each breakpoint location.
The rows for individual locations contain the actual addresses for locations, and show the functions to which those locations belong. The number column for a location is of the form breakpoint-number. However, each location can be individually enabled or disabled by passing breakpoint-number.
Disabling or enabling the parent breakpoint see Disabling affects all of the locations that belong to that breakpoint. Shared libraries can be loaded and unloaded explicitly, and possibly repeatedly, as the program is executed. To support this use case, GDB updates breakpoint locations whenever any shared library is loaded or unloaded.
Typically, you would set a breakpoint in a shared library at the beginning of your debugging session, when the library is not loaded, and when the symbols from the library are not available. When you try to set breakpoint, GDB will ask you if you want to set a so called pending breakpoint—breakpoint whose address is not yet resolved.
After the program is run, whenever a new shared library is loaded, GDB reevaluates all the breakpoints. When a newly loaded shared library contains the symbol or line referred to by some pending breakpoint, that breakpoint is resolved and becomes an ordinary breakpoint. When a library is unloaded, all breakpoints that refer to its symbols or source lines become pending again.
This logic works for breakpoints with multiple locations, too. Except for having unresolved address, pending breakpoints do not differ from regular breakpoints.
You can set conditions or commands, enable and disable them and perform other breakpoint operations. When GDB cannot find the breakpoint location, it queries you whether a pending breakpoint should be created.
Any unrecognized breakpoint location results in an error. This setting does not affect any pending breakpoints previously created. The settings above only affect the break command and its variants.
Once breakpoint is set, it will be automatically updated as shared libraries are loaded and unloaded. For some targets, GDB can automatically decide if hardware or software breakpoints should be used, depending on whether the breakpoint address is read-only or read-write.
This applies to breakpoints set with the break command as well as to internal breakpoints set by commands like next and finish.Debugging Guide for GDB and Eclipse by Brian Fraser Last update: Sept 25, • Change the IP address to the IP address of the target. • The host should look like this: $ gdb-multiarch -q helloWorld Try setting a break-point in a .
8. Examining Data. The usual way to examine data in your program is with the print command info breakpoints (to the address of the last breakpoint listed), The access mode attributes set whether GDB may make read or write accesses to a memory region.
watch only breaks on write, rwatch let you break on read, and awatch let you break on read/write.. You can set read watchpoints on memory locations: gdb$ rwatch *0xfeedface Hardware read watchpoint 2: *0xfeedface but one limitation applies to the rwatch and awatch .
(gdb) info breakpoints Num Type Disp Enb Address What 1 breakpoint keep y 0xf6 in main at try5.c:4 breakpoint already hit 1 time 2 breakpoint keep n 0xa in display at try5.c breakpoint already hit 1 time 3 hw watchpoint keep y i.
break *address Set a breakpoint at address address. You can use this to set breakpoints in parts of your program which do not have debugging information or source files. This will get you quickly to the last hit of that breakpoint.
GDB allows you to set any number of breakpoints at the same place in your program. There is nothing silly or. Beej's Quick Guide to GDB by Brian "Beej Jorgensen" Hall is licensed under a Creative i b Num Type Disp Enb Address What 1 breakpoint keep y 0x in main at hello.c:5 To clear a breakpoint, use the clear command with the this is pretty cool, but I could write a killer front-end for this thing that worked so much better!.