Linux Kernel Module Cheat

38.13.3. gem5 build variants

Analogous to the Linux kernel build variants but with the --gem5-build-id option instead:

# Build master.
./build-gem5

# Build another branch.
git -C "$(./getvar gem5_source_dir)" checkout some-branch
./build-gem5 --gem5-build-id some-branch

# Restore master.
git -C "$(./getvar gem5_source_dir)" checkout -

# Run master.
./run --emulator gem5

# Run another branch.
git -C "$(./getvar gem5_source_dir)" checkout some-branch
./run --gem5-build-id some-branch --emulator gem5

Don’t forget however that gem5 has Python scripts in its source code tree, and that those must match the source code of a given build.

Therefore, you can’t forget to checkout to the sources to that of the corresponding build before running, unless you explicitly tell gem5 to use a non-default source tree with gem5 worktree. This becomes inevitable when you want to launch multiple simultaneous runs at different checkouts.

gem5 worktree
gem5 private source trees