Crash logs are incredibly useful when trying to track down a bug, especially if it's not immediately reproducible.
Obtaining a crash log on Mac OS X is incredibly easy since it automatically creates easily accessible crash logs for you.
If WebKit has just crashed or you can easily reproduce the crash, press the Report button on the CrashReporter dialog box to view the crash information.
Copy and paste the entire contents of the top portion of the CrashReporter window into your favorite text editor and upload it as an attachment in Bugzilla.
If the crash report dialog does not appear or the crash is hard to reproduce, you can get the crash log from the Safari.crash.log file located in ~/Library/Logs/CrashReporter/. This file is a plain text file and can be viewed in the default Console.app or your favorite text editor.
All of Safari's crashes are logged to this file so please only attach the last crash in it. Crashes are separated by a series of asterisks (∗∗∗∗∗∗∗∗∗∗) for easy identification.
Windows XP does not automatically log crashes like OS X, but it does include Dr. Watson, an easy to set up tool that can be configured to log them.
In the Start menu's Run box or from a DOS or Cygwin prompt, enter the command drwtsn32 -i.
A dialog box will appear informing you that Dr. Watson has been installed as the default debugger. Press OK.
Crash information will now be logged to the drwtsn32.log and user.dmp files in C:\Documents and Settings\All Users\Application Data\Microsoft\Dr Watson\.
All crashes you experience on Windows XP are logged to drwtsn32.log. Dr. Watson will also create a user.dmp file that contains a dump of the memory WebKit was using when it crashed. This is generally more useful for debugging a crash than the crash log, but be careful as it is overwritten with every crash.
When reporting a WebKit bug, please only upload the relevant WebKit portion of the drwtsn32.log file as well as the entire user.dmp file if possible.
Running drwtsn32 without any options or switches will bring up a window that allows you to change various setting such as moving the log folder to a more easily accessible location or throwing a visual alert letting you know it caught the crash.