Once you have VSCode installed, open the Trusty code base in VSCode and create a .vscode folder in the root (it may already exist if you've adjusted any settings). This folder is needed to tell the install script where the VSCode workspace begins.
Next run the install script:
$ ./trusty/vendor/google/aosp/ide/vscode/install.sh
This will configure VSCode to understand how to start up Trusty in the emulator and attach the debugger.
The configuration files that are provided do not build Trusty for you. You'll need to do that on the command line:
$ ./trusty/vendor/google/aosp/scripts/build.py --skip-tests qemu-generic-arm64-test-debug
Before starting, go ahead and set your breakpoints by clicking to the left of the line number in a file. You can do this for kernel code as well as TA code. Because our integration with LLDB is hacky, the debugger will lose track of a process after syscalls are made. You'll need to add breakpoints after each syscall to step past them.
As long as you've built the qemu-generic-arm64-test-debug Trusty project you can switch to the Run/Debug view (View > Run) and click the button that says Debug with Prebuilt.
Now you're debugging like a pro.