[gnome-continuous-yocto/gnomeostree-3.28-rocko: 34/218] rootfs-postcommands.bbclass: ensure that rootfs gets mounted ro

[Emmanuele Bassi <ebassi src gnome org>]

commit aab33ec877862a4e55e57a4bab9e636250d63d45
Author: Patrick Ohly <patrick ohly intel com>
Date:   Mon Nov 27 16:56:42 2017 +0100

    rootfs-postcommands.bbclass: ensure that rootfs gets mounted ro
    
    When read-only-rootfs is active, we need to ensure that the rootfs
    does not get mounted read/write by the kernel or initramfs. Adding
    "ro" to the boot parameters achieves that.
    
    (From OE-Core rev: 2b9a670fabf3aefa93dc12be8b2fd3d6226be12a)
    
    Signed-off-by: Patrick Ohly <patrick ohly intel com>
    Signed-off-by: Ross Burton <ross burton intel com>
    (cherry picked from commit cfc09de06ecc12bb42181004689e881c75072665)
    Signed-off-by: Armin Kuster <akuster808 gmail com>
    Signed-off-by: Richard Purdie <richard purdie linuxfoundation org>

 meta/classes/rootfs-postcommands.bbclass |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/meta/classes/rootfs-postcommands.bbclass b/meta/classes/rootfs-postcommands.bbclass
index 5391e7a..a4e627f 100644
--- a/meta/classes/rootfs-postcommands.bbclass
+++ b/meta/classes/rootfs-postcommands.bbclass
@@ -14,6 +14,14 @@ ROOTFS_POSTPROCESS_COMMAND += "rootfs_update_timestamp ; "
 # Tweak the mount options for rootfs in /etc/fstab if read-only-rootfs is enabled
 ROOTFS_POSTPROCESS_COMMAND += '${@bb.utils.contains("IMAGE_FEATURES", "read-only-rootfs", 
"read_only_rootfs_hook; ", "",d)}'
 
+# We also need to do the same for the kernel boot parameters,
+# otherwise kernel or initramfs end up mounting the rootfs read/write
+# (the default) if supported by the underlying storage.
+#
+# We do this with _append because the default value might get set later with ?=
+# and we don't want to disable such a default that by setting a value here.
+APPEND_append = '${@bb.utils.contains("IMAGE_FEATURES", "read-only-rootfs", " ro", "", d)}'
+
 # Generates test data file with data store variables expanded in json format
 ROOTFS_POSTPROCESS_COMMAND += "write_image_test_data ; "