From: Johannes Schneider <johannes.schneider@leica-geosystems.com>
To: openembedded-core@lists.openembedded.org,
richard.purdie@linuxfoundation.org, alex.kanavin@gmail.com,
alexandre.belloni@bootlin.com
Cc: Johannes Schneider <johannes.schneider@leica-geosystems.com>
Subject: [PATCH v9 3/3] classes: add a systemd-sysext image class
Date: Thu, 16 May 2024 00:35:00 +0200 [thread overview]
Message-ID: <20240515223500.3464486-4-johannes.schneider@leica-geosystems.com> (raw)
In-Reply-To: <20240515223500.3464486-1-johannes.schneider@leica-geosystems.com>
systemd-sysext can load a raw-image containing usr/ and opt/ folders
to mount them as RO overlay over the rootfs, to "extend" the systems.
This class provides the necessary changes/additions to the enclosed
file-system so that systemd-sysext accepts the extension for "merge"
into the rootfs.
With such an created image, placed into the correct folder (see [1]),
`systemd-sysext list` should be able to list the "extension" and
`systemd-sysext merge` should enable the overlay. On both commands a
preceding "SYSTEMD_LOG_LEVEL=debug" can aide in figuring out what is
amiss.
The strict name checking systemd-sysext does against the name of
extension-release.NAME file, is disabled, as there is only one such in
the resulting image. This is done to allow a user to freely rename the
resulting image file.
Note that for e.g. squashfs, the kernel needs CONFIG_SQUASHFS_XATTR=y
Link: https://www.freedesktop.org/software/systemd/man/latest/systemd-sysext.html
Link: https://0pointer.net/blog/testing-my-system-code-in-usr-without-modifying-usr.html
Signed-off-by: Johannes Schneider <johannes.schneider@leica-geosystems.com>
---
meta/classes-recipe/image-sysext.bbclass | 43 ++++++++++++++++++++++++
1 file changed, 43 insertions(+)
create mode 100644 meta/classes-recipe/image-sysext.bbclass
diff --git a/meta/classes-recipe/image-sysext.bbclass b/meta/classes-recipe/image-sysext.bbclass
new file mode 100644
index 0000000000..bc3e4d52b5
--- /dev/null
+++ b/meta/classes-recipe/image-sysext.bbclass
@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: MIT
+#
+# Copyright Leica Geosystems AG
+#
+
+# systemd-sysext [1] has a simple mechanism for version compatibility:
+# the extension to be loaded has to contain a
+# /usr/lib/extension-release.d/extension-release.NAME
+# with "NAME" *exactly* matching the filename of the extensions
+# raw-device filename/
+#
+# from the extension-release file the "ID" and "VERSION_ID" fields are
+# matched against the etc/os-release and the extension is only "merged"
+# if no mismatches between NAME, ID, and VERSION_ID.
+#
+# Link: https://www.freedesktop.org/software/systemd/man/latest/systemd-sysext.html
+
+inherit image
+
+IMAGE_NAME_SUFFIX = ".sysext"
+EXTENSION_NAME = "${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.${IMAGE_FSTYPES}"
+IMAGE_LINK_NAME:append = ".sysext"
+
+DEPENDS += " os-release"
+
+sysext_image_mangle_rootfs() {
+ R=${IMAGE_ROOTFS}
+
+ # pull a copy of the rootfs version information, which systemd-sysext matches against
+ cp -av ${RECIPE_SYSROOT}/${nonarch_libdir}/os-release ${WORKDIR}/extension-release.base
+
+ echo 'EXTENSION_RELOAD_MANAGER=1' >> ${WORKDIR}/extension-release.base
+
+ install -d $R${nonarch_libdir}/extension-release.d
+ install -m 0644 ${WORKDIR}/extension-release.base \
+ $R${nonarch_libdir}/extension-release.d/extension-release.${EXTENSION_NAME}
+
+ # disable systemd-sysext's strict name checking, so that the image file can be renamed, while still being 'merge'-able
+ setfattr -n user.extension-release.strict -v false \
+ $R${nonarch_libdir}/extension-release.d/extension-release.${EXTENSION_NAME}
+}
+
+ROOTFS_POSTPROCESS_COMMAND += " sysext_image_mangle_rootfs; "
--
2.34.1
next prev parent reply other threads:[~2024-05-15 22:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-15 22:34 [PATCH v9 0/3] pkg-database and systemd-sysext image Johannes Schneider
2024-05-15 22:34 ` [PATCH v9 1/3] image.bbclass/rootfs: archive and deploy package database Johannes Schneider
2024-05-15 22:34 ` [PATCH v9 2/3] image.bbclass/rootfs: set and unpack package-database Johannes Schneider
2024-05-15 22:35 ` Johannes Schneider [this message]
2024-05-17 18:33 ` [OE-core] [PATCH v9 0/3] pkg-database and systemd-sysext image Alexandre Belloni
2024-05-18 6:30 ` SCHNEIDER Johannes
2024-05-21 10:08 ` Alexander Kanavin
2024-05-22 10:59 ` SCHNEIDER Johannes
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