Friday, July 13, 2018

Written on Jul 13, 2018

Tips for slightly faster debug builds

add_ac_options disable-optimize
add_ac_options enable-optimize=-Og

How I use Mozilla’s rr to debug child processes

• export MOZ_DEBUG_CHILD_PROCESS=1
• rr record -n obj-debug/dist/bin/firefox -no-remote -profile /home/mozilla/gecko/obj-debug/tmp/profile-default
• Note the PPID of the tab/window you want to debug (second column)
• Do things, close browser at the end
• rr replay -p <pid>
• (gdb) handle SIGSYS noprint nostop
• Set up breakpoints wherever, and debug away!

How to debug Mozilla’s rr to debug main processes

• rr record -n obj-debug/dist/bin/firefox -no-remote -profile /home/mozilla/gecko/obj-debug/tmp/profile-default
• Do things, close browser at the end
• rr ps, Grad the PID from the first column of the second process (that’s the main thread)
• rr replay -p <pid>
• (gdb) handle SIGSYS noprint nostop
• Set up breakpoints wherever, and debug away!