Patchwork [V8,2/6] image.bbclass: add a hook funtion to support readonly rootfs

login
register
mail settings
Submitter Qi.Chen@windriver.com
Date Jan. 22, 2013, 6:36 a.m.
Message ID <3d6b90b5ad79166eda3883ad4e9d5ca1ed937f10.1358836314.git.Qi.Chen@windriver.com>
Download mbox | patch
Permalink /patch/43129/
State New
Headers show

Comments

Qi.Chen@windriver.com - Jan. 22, 2013, 6:36 a.m.
From: Chen Qi <Qi.Chen@windriver.com>

read_only_rootfs_hook: this funtion is invoked only if 'read-only-rootfs'
is in IMAGE_FEATURES. It tweaks some basic files and makes populate-
volatile.sh script run at rootfs time.

For now, it has real effect only if the init system is sysvinit.

[YOCTO #3406]

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
---
 meta/classes/image.bbclass |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
mike.looijmans@topic.nl - Jan. 22, 2013, 6:17 p.m.
On 01/22/2013 07:36 AM, Qi.Chen@windriver.com wrote:
> From: Chen Qi <Qi.Chen@windriver.com>
>
> read_only_rootfs_hook: this funtion is invoked only if 'read-only-rootfs'
> is in IMAGE_FEATURES. It tweaks some basic files and makes populate-
> volatile.sh script run at rootfs time.

To me, it seems running populate-volatile at rootfs is a good thing for 
writable rootfs as well, it reduces the writing at first boot. Why not 
ALWAYS do this?
Qi.Chen@windriver.com - Jan. 23, 2013, 6:07 a.m.
On 01/23/2013 02:17 AM, Mike Looijmans wrote:
> On 01/22/2013 07:36 AM, Qi.Chen@windriver.com wrote:
>> From: Chen Qi <Qi.Chen@windriver.com>
>>
>> read_only_rootfs_hook: this funtion is invoked only if 
>> 'read-only-rootfs'
>> is in IMAGE_FEATURES. It tweaks some basic files and makes populate-
>> volatile.sh script run at rootfs time.
>
> To me, it seems running populate-volatile at rootfs is a good thing 
> for writable rootfs as well, it reduces the writing at first boot. Why 
> not ALWAYS do this?
>
Hi Mike,

The reason I didn't make it *always* run at rootfs is that it's not 
*necessary*.
Besides, I want to encapsulate all all necessary tweaks at rootfs time 
into one function -- read-only-rootfs-hook.
In this way, I can ensure that it doesn't mess up with other components.

Thanks,
Chen Qi

Patch

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index 0293d2e..91045fc 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -201,6 +201,24 @@  run_intercept_scriptlets () {
 	fi
 }
 
+# A hook function to support read-only-rootfs IMAGE_FEATURES
+# Currently, it only supports sysvinit system.
+read_only_rootfs_hook () {
+	if ${@base_contains("DISTRO_FEATURES", "sysvinit", "true", "false", d)}; then
+	        # Tweak the mount option in fstab
+		sed -i '/rootfs/ s/defaults/ro/' ${IMAGE_ROOTFS}/etc/fstab
+	        # Change the value of ROOTFS_READ_ONLY in /etc/default/rcS to yes
+		if [ -e ${IMAGE_ROOTFS}/etc/default/rcS ]; then
+			sed -i 's/ROOTFS_READ_ONLY=no/ROOTFS_READ_ONLY=yes/' ${IMAGE_ROOTFS}/etc/default/rcS
+		fi
+	        # Run populate-volatile.sh at rootfs time to set up basic files
+	        # and directories to support read-only rootfs.
+		if [ -e ${IMAGE_ROOTFS}/etc/init.d/populate-volatile.sh ]; then
+			${IMAGE_ROOTFS}/etc/init.d/populate-volatile.sh
+		fi
+	fi
+}
+
 fakeroot do_rootfs () {
 	#set -x
 	# When use the rpm incremental image generation, don't remove the rootfs