docs: Update HACKING.md to mention latest mkosi is needed

Let's require users to run mkosi from git so we can fix any issues
forward instead of trying to keep the configs working with older
versions.

diff --git a/docs/HACKING.md b/docs/HACKING.md
index 979cd58407a80628b50f4efafd58665750dc71d2..96133683f1d7cef53202794e311c333483ef3125 100644 (file)
--- a/docs/HACKING.md
+++ b/docs/HACKING.md
@@ -35,13 +35,14 @@ 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 the
-`mkosi` package (if not packaged for your distro, it can be downloaded from
+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. mkosi-13 or newer version is required.
-It is sufficient to type `mkosi` in the systemd project directory to generate
-a disk image `image.raw` you can boot either in `systemd-nspawn` or
-in an UEFI-capable VM:
+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. 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
 $ mkosi boot
@@ -92,8 +93,7 @@ for systemd:
 
 ```sh
 # Install build dependencies (see above)
-# Install a recent version of mkosi (either via your distro's package manager if
-# available there or from the github repository otherwise)
+# 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
@@ -101,8 +101,11 @@ $ vim src/core/main.c             # or wherever you'd like to make your changes
 $ meson build                     # configure the build
 $ ninja -C build                  # build it locally, see if everything compiles fine
 $ meson test -C build             # run some simple regression tests
-$ sudo mkosi                      # mkosi-13 or newer required to build a test image
-$ sudo mkosi boot                 # boot up the test image
+$ cd ..
+$ git clone https://github.com/systemd/mkosi.git
+$ cd systemd
+$ sudo ../mkosi/bin/mkosi         # build the test image
+$ sudo ../mkosi/bin/mkosi boot    # boot up the test image
 $ git add -p                      # interactively put together your patch
 $ git commit                      # commit it
 $ git push -u <REMOTE>            # where REMOTE is your "fork" on GitHub