_Software Counters mode_ `rr` is a reverse debugger built upon the awesome `rr` debugger.<p>It relaxes one major limitation with the `rr` debugger - it does NOT require access to CPU HW performance counters.<p>This allows the debugger to run in containers, cloud VMs etc where access to CPU performance counters is usually disabled or not available.<p>In case you're wondering: reverse debugging is a powerful approach to locating bugs in your program using record/replay. Please see the blog post (<a href="https://github.com/sidkshatriya/me/blob/master/008-rr-everywhere.md" rel="nofollow">https://github.com/sidkshatriya/me/blob/master/008-rr-everyw...</a>) for a gentle exposition of the concept behind record/replay.