Update HACKING instructions

Let's mention that we just need the latest stable release of mkosi,
not the latest git commit. We also split the instructions for building
on the host and the instructions for building with mkosi into two blocks,
as it's not required to build on the host anymore to build with mkosi.

1 files changed, 30 insertions, 33 deletions

diff --git a/docs/HACKING.md b/docs/HACKING.md
index dcafbe8e18..09bc5b5fff 100644
--- a/docs/HACKING.md
+++ b/docs/HACKING.md
@@ -35,16 +35,13 @@ possible, however. In order to simplify testing for cases like this we provide
 a set of `mkosi` build files directly in the source tree.
 [mkosi](https://github.com/systemd/mkosi) is a tool for building clean OS images
 from an upstream distribution in combination with a fresh build of the project
-in the local working directory. To make use of this, please install `mkosi` from
-the [GitHub repository](https://github.com/systemd/mkosi). `mkosi` will build an
-image for the host distro by default. Currently, the latest github commit is
-required. `mkosi` also requires systemd v253 (unreleased) or newer. If systemd v253
-is not available, `mkosi` will automatically use executables from the systemd build
-directory if it's executed from the systemd repository root directory. First, run
-`mkosi genkey` to generate a key and certificate to be used for secure boot and
-verity signing. After that is done, it is sufficient to type `mkosi` in the systemd
-project directory to generate a disk image you can boot either in `systemd-nspawn`
-or in a UEFI-capable VM:
+in the local working directory. To make use of this, please install `mkosi` v18
+or newer using your distribution's package manager or from the
+[GitHub repository](https://github.com/systemd/mkosi). `mkosi` will build an
+image for the host distro by default. First, run `mkosi genkey` to generate a key
+and certificate to be used for secure boot and verity signing. After that is done,
+it is sufficient to type `mkosi` in the systemd project directory to generate a disk
+image you can boot either in `systemd-nspawn` or in a UEFI-capable VM:
 
 ```sh
 $ sudo mkosi boot # nspawn still needs sudo for now
@@ -59,8 +56,26 @@ $ mkosi qemu
 Every time you rerun the `mkosi` command a fresh image is built, incorporating
 all current changes you made to the project tree.
 
+Putting this all together, here's a series of commands for preparing a patch
+for systemd:
+
+```sh
+$ git clone https://github.com/systemd/mkosi.git  # If mkosi v18 or newer is not packaged by your distribution
+$ ln -s $PWD/mkosi/bin/mkosi /usr/local/bin/mkosi # If mkosi v18 or newer is not packaged by your distribution
+$ git clone https://github.com/systemd/systemd.git
+$ 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
+$ git add -p                      # interactively put together your patch
+$ git commit                      # commit it
+$ git push -u <REMOTE>            # where REMOTE is your "fork" on GitHub
+```
+
+And after that, head over to your repo on GitHub and click "Compare & pull request"
+
 If you want to do a local build without mkosi, most distributions also provide
-very simple and convenient ways to install all development packages necessary
+very simple and convenient ways to install most development packages necessary
 to build systemd:
 
 ```sh
@@ -75,32 +90,14 @@ $ cd systemd
 $ makepkg -seoc
 ```
 
-Putting this all together, here's a series of commands for preparing a patch
-for systemd:
+After installing the development packages, systemd can be built from source as follows:
 
 ```sh
-# Install build dependencies (see above)
-# Install mkosi from the github repository
-$ git clone https://github.com/systemd/systemd.git
-$ 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
-$ meson setup build -Danalyze=true -Drepart=true -Defi=true -Dbootloader=true -Dukify=true # configure the build
-$ ninja -C build                  # build it locally, see if everything compiles fine
-$ meson test -C build             # run some simple regression tests
-$ cd ..
-$ git clone https://github.com/systemd/mkosi.git
-$ ln -s mkosi/bin/mkosi ~/.local/bin/mkosi # Make sure ~/.local/bin is in $PATH
-$ cd systemd
-$ mkosi                           # build the test image
-$ mkosi qemu                      # boot up the test image in qemu
-$ git add -p                      # interactively put together your patch
-$ git commit                      # commit it
-$ git push -u <REMOTE>            # where REMOTE is your "fork" on GitHub
+$ meson setup build <options>
+$ ninja -C build
+$ meson test -C build
 ```
 
-And after that, head over to your repo on GitHub and click "Compare & pull request"
-
 Happy hacking!
 
 ## Templating engines in .in files