On Linux, Chromium can use Breakpad to generate minidump files for crashes. It is possible to convert the minidump files to core files, and examine the core file in gdb, cgdb, or Qtcreator. In the examples below cgdb is assumed but any gdb based debugger can be used.
minidump-2-core to convert the minidump file to a core file. On Linux, one can build the minidump-2-core target in a Chromium checkout, or alternatively, build it in a Google Breakpad checkout.
$ ninja -C out/Release minidump-2-core $ ./out/Release/minidump-2-core foo.dmp > foo.core
If the minidump is from a public build then Googlers can find Google Chrome Linux binaries and debugging symbols via https://goto.google.com/chromesymbols. Otherwise, use the locally built chrome files. Google Chrome uses the debug link method to specify the debugging file. Either way be sure to put
chrome.debug (the stripped debug information) in the same directory as the core file so that the debuggers can find them.
For Chrome OS release binaries look for
debug-*.tgz files on GoldenEye.
The recommended syntax for loading a core file into gdb/cgdb is as follows, specifying both the executable and the core file:
$ cgdb chrome foo.core
If the executable is not available then the core file can be loaded on its own but debugging options will be limited:
$ cgdb -c foo.core
Qtcreator is a full GUI wrapper for gdb and it can also load Chrome's core files. From Qtcreator select the Debug menu, Start Debugging, Load Core File... and then enter the paths to the core file and executable. Qtcreator has windows to display the call stack, locals, registers, etc. For more information on debugging with Qtcreator see Getting Started Debugging on Linux.
If you have a Chromium repo that is synchronized to exactly (or even approximately) when the Chrome build was created then you can tell
gdb/cgdb/Qtcreator to load source code. Since all source paths in Chrome are relative to the out/Release directory you just need to add that directory to your debugger search path, by adding a line similar to this to
(gdb) directory /usr/local/chromium/src/out/Release/
add-symbol-filecommand to work, the file must have debugging symbols.
If gdb doesn't find shared objects that are needed you can force it to load them. In gdb, the
add-symbol-file command takes a filename and an address. To figure out the address, look near the end of
foo.dmp, which contains a copy of
/proc/pid/maps from the process that crashed.
One quick way to do this is with
grep. For instance, if the executable is
/path/to/chrome, one can simply run:
$ grep -a /path/to/chrome$ foo.dmp 7fe749a90000-7fe74d28f000 r-xp 00000000 08:07 289158 /path/to/chrome 7fe74d290000-7fe74d4b7000 r--p 037ff000 08:07 289158 /path/to/chrome 7fe74d4b7000-7fe74d4e0000 rw-p 03a26000 08:07 289158 /path/to/chrome
In this case,
7fe749a90000 is the base address for
/path/to/chrome, but gdb takes the start address of the file's text section. To calculate this, one will need a copy of
/path/to/chrome, and run:
$ objdump -x /path/to/chrome | grep '\.text' | head -n 1 | tr -s ' ' | \ cut -d' ' -f 7 005282c0
Now add the two addresses:
7fe749a90000 + 005282c0 = 7fe749fb82c0 and in gdb, run:
(gdb) add-symbol-file /path/to/chrome 0x7fe749fb82c0
Then use gdb as normal.
For more discussion on this process see [Debugging a Minidump]. This page discusses the same process in the context of Chrome OS and many of the concepts and techniques overlap.