debugging - Can I set a breakpoint on 'memory access' in GDB? -

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i running application through gdb , want set breakpoint time specific variable accessed / changed. there method doing this? interested in other ways monitor variable in c/c++ see if/when changes.

watch breaks on write, rwatch let break on read, , awatch let break on read/write.

you can set read watchpoints on memory locations:

gdb$ rwatch *0xfeedface hardware read watchpoint 2: *0xfeedface

but 1 limitation applies rwatch , awatch commands; can't use gdb variables in expressions:

gdb$ rwatch $ebx+0xec1a04f expression cannot implemented read/access watchpoint.

so have expand them yourself: 

gdb$ print $ebx  $13 = 0x135700 gdb$ rwatch *0x135700+0xec1a04f hardware read watchpoint 3: *0x135700 + 0xec1a04f gdb$ c hardware read watchpoint 3: *0x135700 + 0xec1a04f  value = 0xec34daf 0x9527d6e7 in objc_msgsend ()

edit: oh, , way. need either hardware or software support. software slower. find out if os supports hardware watchpoints can see can-use-hw-watchpoints environment setting. 

gdb$ show can-use-hw-watchpoints debugger's willingness use watchpoint hardware 1.

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