Merge pull request #24629 from DaanDeMeyer/mkosi-kernel

mkosi: Optionally build a kernel image from mkosi.kernel/

docs/HACKING.md

@@ -414,3 +414,23 @@ To debug systemd-boot in an IDE such as VSCode we can use a launch configuration
     ]
 }
 ```
+
+## Hacking on the kernel + systemd
+
+If you're hacking on the kernel in tandem with systemd, you can clone a kernel repository in mkosi.kernel/ in
+the systemd repository, and mkosi will automatically build that kernel and install it into the final image.
+To prevent the distribution's kernel from being installed (which isn't necessary since we're building our
+own kernel), you can add the following snippets to mkosi.default.d/20-local.conf:
+
+(This snippet is for Fedora, the list of packages will need to be changed for other distributions)
+
+```
+[Distribution]
+CacheInitrd=no
+
+[Content]
+BasePackages=conditional
+Packages=systemd
+         util-linux
+         dracut
+```

mkosi.build

@@ -259,3 +259,40 @@ fi
 # Make sure services aren't enabled by default on Debian/Ubuntu.
 mkdir -p "$DESTDIR/etc/systemd/system-preset"
 echo "disable *" > "$DESTDIR/etc/systemd/system-preset/99-mkosi.preset"
+
+if [ -d mkosi.kernel/ ]; then
+        cd "$SRCDIR/mkosi.kernel"
+        mkdir -p "$BUILDDIR/mkosi.kernel"
+
+        make O="$BUILDDIR/mkosi.kernel" defconfig
+
+        scripts/config \
+                --file $BUILDDIR/mkosi.kernel/.config \
+                --enable BPF_SYSCALL \
+                --enable BPF_JIT \
+                --enable BPF_JIT_ALWAYS_ON \
+                --enable BPF_JIT_DEFAULT_ON \
+                --enable BPF_UNPRIV_DEFAULT_OFF \
+                --enable USERMODE_DRIVER \
+                --enable BPF_PRELOAD \
+                --enable BPF_PRELOAD_UMD \
+                --enable BPF_LSM \
+                --enable BTRFS_FS \
+                --enable BTRFS_FS_POSIX_ACL \
+                --enable PSI \
+                --enable CGROUPS \
+                --enable CGROUP_BPF \
+                --enable MEMCG \
+                --enable MEMCG_SWAP \
+                --enable MEMCG_KMEM
+
+        # Make sure all unset options are set to their default value.
+        make O="$BUILDDIR/mkosi.kernel" olddefconfig
+
+        make O="$BUILDDIR/mkosi.kernel" -j "$(nproc)"
+
+        KERNEL_RELEASE="$(make O=$BUILDDIR/mkosi.kernel -s kernelrelease)"
+        mkdir -p "$DESTDIR/usr/lib/modules/$KERNEL_RELEASE"
+        make O="$BUILDDIR/mkosi.kernel" INSTALL_MOD_PATH="$DESTDIR/usr" modules_install
+        make O="$BUILDDIR/mkosi.kernel" INSTALL_PATH="$DESTDIR/usr/lib/modules/$KERNEL_RELEASE" install
+fi

mkosi.default.d/10-systemd.conf

@@ -13,6 +13,7 @@ OutputDirectory=mkosi.output
 [Content]
 BuildDirectory=mkosi.builddir
 Cache=mkosi.cache
+SourceFileTransfer=mount
 SourceFileTransferFinal=copy-git-others
 Packages=
         acl
@@ -42,17 +43,23 @@ Packages=
         zsh
 
 BuildPackages=
+        bc
+        binutils
+        bison
         clang
+        flex
         gcc
         gettext
         git
         gnu-efi
         gperf
         llvm
+        make
         meson
         pkgconf
         rpm
         rsync
+        tar
         zstd
 
 [Host]

mkosi.default.d/arch/10-mkosi.arch

@@ -31,6 +31,7 @@ BuildPackages=
         docbook-xsl
         libxslt
         linux-api-headers
+        pahole
         perl
         python-jinja
         python-lxml

mkosi.default.d/centos_epel/10-mkosi.centos_epel

@@ -38,6 +38,7 @@ Packages=
 BuildPackages=
         bpftool
         docbook-xsl
+        dwarves
         gnu-efi-devel
         libgcrypt-devel # CentOS Stream 8 libgcrypt-devel doesn't ship a pkg-config file.
         libxslt

mkosi.default.d/debian/10-mkosi.debian

@@ -63,6 +63,7 @@ BuildPackages=
         libssl-dev
         libxkbcommon-dev
         libzstd-dev
+        pahole
         python3-jinja2
         python3-lxml
         xsltproc

mkosi.default.d/fedora/10-mkosi.fedora

@@ -17,7 +17,6 @@ Packages=
         gnutls
         iproute
         iproute-tc
-        kernel-modules-extra
         libbpf
         libfido2
         libmicrohttpd
@@ -34,6 +33,7 @@ Packages=
 BuildPackages=
         bpftool
         docbook-xsl
+        dwarves
         gnu-efi-devel
         pam-devel
         pkgconfig # pkgconf shim to provide /usr/bin/pkg-config

mkosi.default.d/opensuse/10-mkosi.opensuse

@@ -35,6 +35,7 @@ BuildPackages=
         bpftool
         dbus-1-devel
         docbook-xsl-stylesheets
+        dwarves
         fdupes
         gcc-c++
         glib2-devel

mkosi.default.d/ubuntu/10-mkosi.ubuntu

@@ -64,6 +64,7 @@ BuildPackages=
         libssl-dev
         libxkbcommon-dev
         libzstd-dev
+        pahole
         python3-jinja2
         python3-lxml
         xsltproc