[DistroKit] [PATCH v2 09/10] rauc-udev: generate symlinks based on GPT partition labels

[Roland Hieber <rhi@pengutronix.de>]

Now that all our images have a GPT header which contains partitions
with the labels "root-A", "root-B", and "data", we can use those to
generate the symlinks in /dev/disk/by-usage/ instead of using the
hardcoded, number-based kernel device names. This gives us the
flexibility to change the order of the partitions on disk as long as
their GPT partition labels stay the same.

Since the symlinks in /dev/disk/by-partlabel/ are not necessarily unique
(see [1]), we cannot use these here. Instead, rework the current match
clauses to determine the devpath of the boot device based on the board
compatible, and only create by-usage symlinks for partitions on the boot
device.

  [1]: https://github.com/systemd/systemd/pull/29219

Signed-off-by: Roland Hieber <rhi@pengutronix.de>
---
 .../lib/udev/rules.d/90-rauc-partitions.rules | 54 +++++++------------
 1 file changed, 18 insertions(+), 36 deletions(-)

diff --git a/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules b/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules
index e909df01958f..64f1aab46ac0 100644
--- a/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules
+++ b/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules
@@ -8,42 +8,24 @@ IMPORT{program}="of_base_compatible"
 
 # Add symlinks named /dev/disk/by-usage/{data,rootfs0,rootfs1} pointing
 # to the correct partitions based on the device tree compatible
-ENV{OF_BASE_COMPATIBLE}!="*arm,vexpress,v2p-ca9*", GOTO="qemu_vexpress_end"
-KERNEL=="mmcblk0p1", SYMLINK+="disk/by-usage/rootfs0"
-KERNEL=="mmcblk0p2", SYMLINK+="disk/by-usage/rootfs1"
-KERNEL=="mmcblk0p3", SYMLINK+="disk/by-usage/data"
-GOTO="rauc_partitions_end"
-LABEL="qemu_vexpress_end"
-
-ENV{OF_BASE_COMPATIBLE}!="*lxa,stm32mp157c-mc1*", GOTO="lxa_mc1_end"
-KERNEL=="mmcblk0p6", SYMLINK+="disk/by-usage/rootfs0"
-KERNEL=="mmcblk0p7", SYMLINK+="disk/by-usage/rootfs1"
-KERNEL=="mmcblk0p8", SYMLINK+="disk/by-usage/data"
-GOTO="rauc_partitions_end"
-LABEL="lxa_mc1_end"
-
-ENV{OF_BASE_COMPATIBLE}!="*ti,am335x-bone-black*", GOTO="beaglebone_black_end"
-KERNEL=="mmcblk0p2", SYMLINK+="disk/by-usage/rootfs0"
-KERNEL=="mmcblk0p3", SYMLINK+="disk/by-usage/rootfs1"
-KERNEL=="mmcblk0p4", SYMLINK+="disk/by-usage/data"
-GOTO="rauc_partitions_end"
-LABEL="beaglebone_black_end"
-
-ENV{OF_BASE_COMPATIBLE}!="*raspberrypi,3-model-b*", GOTO="rpi3_end"
-KERNEL=="mmcblk0p2", SYMLINK+="disk/by-usage/rootfs0"
-KERNEL=="mmcblk0p3", SYMLINK+="disk/by-usage/rootfs1"
-KERNEL=="mmcblk0p4", SYMLINK+="disk/by-usage/data"
-GOTO="rauc_partitions_end"
-LABEL="rpi3_end"
-
-ENV{OF_BASE_COMPATIBLE}!="*riot,imx6s-riotboard*", GOTO="riotboard_end"
-KERNEL=="mmcblk2p1", SYMLINK+="disk/by-usage/rootfs0"
-KERNEL=="mmcblk2p2", SYMLINK+="disk/by-usage/rootfs1"
-KERNEL=="mmcblk2p3", SYMLINK+="disk/by-usage/data"
-GOTO="rauc_partitions_end"
-LABEL="riotboard_end"
-
-# fallback for boards not yet supported by RAUC
+
+# first part: find out the boot disk on known platforms
+ENV{OF_BASE_COMPATIBLE}=="*arm,vexpress,v2p-ca9*", ENV{ID_PATH}=="platform-bus@40000000:motherboard-bus@40000000:iofpga@7,00000000-amba-10005000.mmci", TAG+="boot_disk"
+ENV{OF_BASE_COMPATIBLE}=="*lxa,stm32mp157c-mc1*", ENV{ID_PATH}=="platform-soc-amba-58005000.mmc", TAG+="boot_disk"
+ENV{OF_BASE_COMPATIBLE}=="*ti,am335x-bone-black*", ENV{ID_PATH}=="platform-48060000.mmc", TAG+="boot_disk"
+ENV{OF_BASE_COMPATIBLE}=="*raspberrypi,3-model-b*", ENV{ID_PATH}=="platform-3f202000.mmc", TAG+="boot_disk"
+ENV{OF_BASE_COMPATIBLE}=="*riot,imx6s-riotboard*", ENV{ID_PATH}=="platform-2198000.mmc", TAG+="boot_disk"
+
+# second part: create /dev/disk/by-usage/ symlinks
+ENV{DEVTYPE}!="partition", GOTO="rauc_partitions_end"
+
+# fallback for boards not yet supported by RAUC;
+# this will get overwritten below if we detected the boot disk
 KERNEL=="mmcblk0p3", SYMLINK+="disk/by-usage/data"
 
+# symlinks based on GPT partition labels
+TAGS=="boot_disk", ENV{ID_PART_ENTRY_NAME}=="root-A", SYMLINK+="disk/by-usage/rootfs0"
+TAGS=="boot_disk", ENV{ID_PART_ENTRY_NAME}=="root-B", SYMLINK+="disk/by-usage/rootfs1"
+TAGS=="boot_disk", ENV{ID_PART_ENTRY_NAME}=="data",   SYMLINK+="disk/by-usage/data"
+
 LABEL="rauc_partitions_end"
-- 
2.39.2