OpenOCD

OpenOCD

This is often bundled as part of a build tools suite.

Build Tool Suites which include OpenOCD

There is a debian package for OpenOCD, but it is unfortunately out of date.

The other option is to build OpenOCD from source

Use openocd and gdb

For more details on how to use gdb, Read the manual. I prefer ddd, which is the graphical interface to gdb.