read-only rootfs support

From: Chen Qi <[email protected]>

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.

Quoted 5 lines · On 01/22/2013 07:36 AM, [email protected] wrote:

From: Chen Qi <[email protected]>

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?

From: Chen Qi <[email protected]>

This recipe provides a config file for core-image-minimal. This config file is used for volatile storage handling in case of a readonly rootfs.

Also, let core-image-minimal depend on this recipe.

[YOCTO #3406]

Signed-off-by Chen Qi <[email protected]>

---
  meta/recipes-core/images/core-image-minimal.bb     |    3 +++
  .../files/volatiles-readonly-minimal               |    8 ++++++++
  .../volatile-conf-minimal_1.0.bb                   |   15 +++++++++++++++
  3 files changed, 26 insertions(+)

create mode 100644 meta/recipes-core/readonly-volatile-conf/files/volatiles-readonly-minimal create mode 100644 meta/recipes-core/readonly-volatile-conf/volatile-conf-minimal_1.0.bb

meta/recipes-core/images/core-image-minimal.bb +0 -0

index 0d2613e..f6baeae 100644

meta/recipes-core/images/core-image-minimal.bb +0 -0

  inherit core-image
 
  IMAGE_ROOTFS_SIZE = "8192"

meta/recipes-core/readonly-volatile-conf/files/volatiles-readonly-minimal new file +8 -0

new file mode 100644
index 0000000..b7146a2
@@ -0,0 +1,8 @@
+# This configuration file lists filesystem objects specific to minimal image
+# with read-only rootfs.
+# This configuration file will only be applied if the image is minimal and the
+# rootfs is read-only.
+# For the detailed format information, refer to /etc/default/volatiles/00_core.
+d root root 0755 /var/volatile/lib/ none
+d root root 0755 /var/volatile/lib/urandom/ none
+l root root 0755 /var/lib/urandom /var/volatile/lib/urandom

meta/recipes-core/readonly-volatile-conf/volatile-conf-minimal_1.0.bb new file +15 -0

new file mode 100644
index 0000000..c5744e1
@@ -0,0 +1,15 @@
+SUMMARY = "Provide config files for core-image-minimal"
+DESCRIPTION = "This package contains a config file for core-image-minimal. \
+It is used to handle volatile storage in case of a read-only rootfs."
+
+LICENSE = "MIT"
+LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"
+
+SRC_URI = "file://volatiles-readonly-minimal"
+
+PR = "r1"
+
+do_install () {
+	install -d ${D}${sysconfdir}/default/volatiles
+	install -m 0644 ${WORKDIR}/volatiles-readonly-minimal ${D}${sysconfdir}/default/volatiles/00_core_readonly
+}

Quoted 30 lines · On 01/21/2013 10:36 PM, [email protected] wrote:

From: Chen Qi <[email protected]>

This recipe provides a config file for core-image-minimal. This config file is used for volatile storage handling in case of a readonly rootfs.

Also, let core-image-minimal depend on this recipe.

[YOCTO #3406]

Signed-off-by Chen Qi <[email protected]>

---
  meta/recipes-core/images/core-image-minimal.bb     |    3 +++
  .../files/volatiles-readonly-minimal               |    8 ++++++++
  .../volatile-conf-minimal_1.0.bb                   |   15 
+++++++++++++++
  3 files changed, 26 insertions(+)

create mode 100644
meta/recipes-core/readonly-volatile-conf/files/volatiles-readonly-minimal
create mode 100644
meta/recipes-core/readonly-volatile-conf/volatile-conf-minimal_1.0.bb

meta/recipes-core/images/core-image-minimal.bb +0 -0

index 0d2613e..f6baeae 100644
@@ -6,6 +6,9 @@ IMAGE_LINGUAS = " "
 
  LICENSE = "MIT"
 

meta/recipes-core/images/core-image-minimal.bb IMAGE_LINGUAS = " " · line 9

Quoted 1 line

meta/recipes-core/images/core-image-minimal.bb +1 -0

+RDEPENDS += "volatile-conf-minimal"

This needs to be RDEPENDS_${PN}

meta/recipes-core/images/core-image-minimal.bb IMAGE_LINGUAS = " " · line 11

Quoted 2 lines

meta/recipes-core/images/core-image-minimal.bb +2 -0

+IMAGE_INSTALL += "volatile-conf-minimal"
+

I am still digging into this idea of having a image specific volatile package, RP is not wild about it either. What's different now from before is the minimal version cut down from the orignal version? Is there any reason we can't use a larger volatile conf?

Sau!

Quoted 36 lines · Saul Wold

Quoted 29 lines · On 01/21/2013 10:36 PM, [email protected] wrote:

From: Chen Qi <[email protected]>

This recipe provides a config file for core-image-minimal. This config file is used for volatile storage handling in case of a readonly rootfs.

Also, let core-image-minimal depend on this recipe.

[YOCTO #3406]

Signed-off-by Chen Qi <[email protected]>

---
  meta/recipes-core/images/core-image-minimal.bb     |    3 +++
  .../files/volatiles-readonly-minimal               |    8 ++++++++
  .../volatile-conf-minimal_1.0.bb                   |   15
+++++++++++++++
  3 files changed, 26 insertions(+)

create mode 100644
meta/recipes-core/readonly-volatile-conf/files/volatiles-readonly-minimal

create mode 100644
meta/recipes-core/readonly-volatile-conf/volatile-conf-minimal_1.0.bb

meta/recipes-core/images/core-image-minimal.bb +0 -0

index 0d2613e..f6baeae 100644

meta/recipes-core/images/core-image-minimal.bb IMAGE_LINGUAS = " " · line 9

Quoted 4 lines

meta/recipes-core/images/core-image-minimal.bb +1 -0

@@ -6,6 +6,9 @@ IMAGE_LINGUAS = " "
 
  LICENSE = "MIT"
 
+RDEPENDS += "volatile-conf-minimal"

This needs to be RDEPENDS_${PN}

Quoted 9 lines

meta/recipes-core/images/core-image-minimal.bb IMAGE_LINGUAS = " " · line 11

Quoted 2 lines

meta/recipes-core/images/core-image-minimal.bb +2 -0

+IMAGE_INSTALL += "volatile-conf-minimal"
+

I am still digging into this idea of having a image specific volatile package, RP is not wild about it either. What's different now from before is the minimal version cut down from the orignal version? Is there any reason we can't use a larger volatile conf?

Sau!

Hi Saul,

I thought about this, but didn't dig deep into it because I thought one conf file for one image would be clearer.
On a second thought, maybe we could use a config file like below.

<pkg1>
readonly specific config items for pkg1
</pkg1>

<pkg2>
readonly specific config items for pkg2
</pkg2>

....
(Let's denote it as the original config file.)

In this way, all config items are centred into one place. And the strategy would be like:
1. get a list of pkgs that are to be installed on target

     L = [pkg1, pkg2, ..., pkgn]

2. original config file -- [select items according to L] --> final config file
The selecting procedure is simply something like:
for pkg in $pkgs; do cat origin | sed -ne "/<$pkg>/,/<\/$pkg>/ {
/<$pkg>/n; /<\/$pkg>/n; p; }" ; done > final
The final config file should look like the ones that we use for now
so that we can still use populate-volatile.sh to create the dirs and links.
3. Parse the final config file with populate-volatile.sh to create the proper directories and links.

The problem is that I don't know how to get the pkg list. Could somebody help me?

What do you think about this strategy?

Cheers,
Chen Qi

Quoted 78 lines · ChenQi

Quoted 37 lines · Saul Wold

Quoted 30 lines · On 01/21/2013 10:36 PM, [email protected] wrote:

From: Chen Qi <[email protected]>

This recipe provides a config file for core-image-minimal. This config file is used for volatile storage handling in case of a readonly rootfs.

Also, let core-image-minimal depend on this recipe.

[YOCTO #3406]

Signed-off-by Chen Qi <[email protected]>

---
  meta/recipes-core/images/core-image-minimal.bb     |    3 +++
  .../files/volatiles-readonly-minimal               |    8 ++++++++
  .../volatile-conf-minimal_1.0.bb                   |   15
+++++++++++++++
  3 files changed, 26 insertions(+)

create mode 100644
meta/recipes-core/readonly-volatile-conf/files/volatiles-readonly-minimal

create mode 100644
meta/recipes-core/readonly-volatile-conf/volatile-conf-minimal_1.0.bb

meta/recipes-core/images/core-image-minimal.bb +0 -0

index 0d2613e..f6baeae 100644

meta/recipes-core/images/core-image-minimal.bb IMAGE_LINGUAS = " " · line 9

Quoted 4 lines

meta/recipes-core/images/core-image-minimal.bb +1 -0

@@ -6,6 +6,9 @@ IMAGE_LINGUAS = " "
 
  LICENSE = "MIT"
 
+RDEPENDS += "volatile-conf-minimal"

This needs to be RDEPENDS_${PN}

Quoted 9 lines

meta/recipes-core/images/core-image-minimal.bb IMAGE_LINGUAS = " " · line 11

Quoted 2 lines

meta/recipes-core/images/core-image-minimal.bb +2 -0

+IMAGE_INSTALL += "volatile-conf-minimal"
+

I am still digging into this idea of having a image specific volatile package, RP is not wild about it either. What's different now from before is the minimal version cut down from the orignal version? Is there any reason we can't use a larger volatile conf?

Sau!

Hi Saul,

I thought about this, but didn't dig deep into it because I thought one conf file for one image would be clearer.
On a second thought, maybe we could use a config file like below.

<pkg1>
readonly specific config items for pkg1
</pkg1>

<pkg2>
readonly specific config items for pkg2
</pkg2>

....
(Let's denote it as the original config file.)

In this way, all config items are centred into one place. And the strategy would be like:
1. get a list of pkgs that are to be installed on target

     L = [pkg1, pkg2, ..., pkgn]

2. original config file -- [select items according to L] --> final config file
The selecting procedure is simply something like:
for pkg in $pkgs; do cat origin | sed -ne "/<$pkg>/,/<\/$pkg>/ {
/<$pkg>/n; /<\/$pkg>/n; p; }" ; done > final
The final config file should look like the ones that we use for now
so that we can still use populate-volatile.sh to create the dirs and links.
3. Parse the final config file with populate-volatile.sh to create the proper directories and links.

Quoted 5 lines

The problem is that I don't know how to get the pkg list. Could somebody help me?

What do you think about this strategy?

Hmm, once you put it this way, another thought came to mind we could create a volatile class similar to update-rc.d or useradd where we specify the a VOLATILE_PKGS, VOLATILE_DIR, VOLATILE_LINK in the appropriate recipes directly and then inherit the volatile class.

Thoughts?

Sau!

Quoted 8 lines

Cheers,
Chen Qi