docs: Update HACKING

Let's mention the new way to install the latest changes without
rebuilding the image. Let's also remove the duplicate info about
distribution packages that is already mentioned in its own section.

diff --git a/docs/HACKING.md b/docs/HACKING.md
index cbf2d45565f986d993427b8c9df423e40be2047f..5a00f1bfd540380adde7d35694ee6132b9f8b1d6 100644 (file)
--- a/docs/HACKING.md
+++ b/docs/HACKING.md
@@ -74,31 +74,21 @@ RuntimeBuildSources=yes
 
 After enabling this setting, the source and build directories will be mounted to
 `/work/src` and `/work/build` respectively when booting the image as a container
-or virtual machine. To build the latest changes and re-install, run
-`meson install -C /work/build --only-changed` in the container or virtual machine
-and optionally restart the daemon(s) you're working on using
-`systemctl restart <units>` or `systemctl daemon-reexec` if you're working on pid1
-or `systemctl soft-reboot` to restart everything.
-
-Aside from the image, the `mkosi.output` directory will also be populated with a
-set of distribution packages. Assuming you're running the same distribution and
-release as the mkosi image, you can install these rpms on your host or test
-system as well for any testing or debugging that cannot easily be performed in a
-VM or container.
-
-By default, no debuginfo packages are produced. To produce debuginfo packages,
-run mkosi with the `WITH_DEBUG` environment variable set to `1`:
+or virtual machine. To build the latest changes and re-install after booting the
+image, run `mkosi -t none` in another terminal on the host and run one of the
+following commands in the container or virtual machine depending on the
+distribution:
 
 ```sh
-$ mkosi -E WITH_DEBUG=1 -f
+dnf upgrade --disablerepo="*" /work/build/*.rpm # CentOS/Fedora
+apt install --reinstall /work/build/*.deb # Debian/Ubuntu
+pacman -U /work/build/*.pkg.tar # Arch Linux
+zypper install --allow-unsigned-rpm /work/build/*.rpm # OpenSUSE
 ```
 
-or configure it in `mkosi.local.conf`:
-
-```conf
-[Content]
-Environment=WITH_DEBUG=1
-```
+and optionally restart the daemon(s) you're working on using
+`systemctl restart <units>` or `systemctl daemon-reexec` if you're working on
+pid1 or `systemctl soft-reboot` to restart everything.
 
 Putting this all together, here's a series of commands for preparing a patch for systemd:
 
@@ -110,6 +100,7 @@ $ cd systemd
 $ git checkout -b <BRANCH>        # where BRANCH is the name of the branch
 $ vim src/core/main.c             # or wherever you'd like to make your changes
 $ mkosi -f qemu                   # (re-)build and boot up the test image in qemu
+$ mkosi -t none                   # Build new packages without rebuilding the image
 $ git add -p                      # interactively put together your patch
 $ git commit                      # commit it
 $ git push -u <REMOTE>            # where REMOTE is your "fork" on GitHub