Re: [PATCH V5 2/4] image.bbclass: add two hook funtions

[ChenQi <Qi.Chen@windriver.com>]

On 01/05/2013 02:47 PM, ChenQi wrote:
> Hi Otavio,
>
> Thank you for you review and suggestions :)
> And please see some details below.
>
> On 01/02/2013 02:12 AM, Otavio Salvador wrote:
>> On Mon, Dec 31, 2012 at 12:16 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.
>>>
>>> choose_volatile_conf_file: this function is invoked no matter
>>> 'read-only-rootfs' is in IMAGE_FEATURES or not, it properly chooses
>>> the right conf file for volatile storage handling according to the
>>> IMAGE_FEATURES.
>>>
>>> [YOCTO #3406]
>>>
>>> Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
>>> ---
>>>   meta/classes/image.bbclass |   30 ++++++++++++++++++++++++++++++
>>>   1 file changed, 30 insertions(+)
>>>
>>> diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
>>> index d3a416d..57bd0e3 100644
>>> --- a/meta/classes/image.bbclass
>>> +++ b/meta/classes/image.bbclass
>>> @@ -396,6 +396,36 @@ zap_root_password () {
>>>          mv ${IMAGE_ROOTFS}/etc/passwd.new ${IMAGE_ROOTFS}/etc/passwd
>>>   }
>>>
>>> +# A hook function to support read-only-rootfs IMAGE_FEATURES
>>> +read_only_rootfs_hook () {
>>> +       # Tweak the mount option in fstab
>>> +       sed -i '/rootfs/ s/defaults/ro/' ${IMAGE_ROOTFS}/etc/fstab
>> Maybe use 'defaults,ro' in fstab?
> In my understanding, 'ro' and 'defaults,ro' are the same. Maybe I'm 
> wrong, but what's the difference between them?
>>> +       # 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
>>> +}
>>> +
>>> +# Choose the correct config file for volatile storage handling 
>>> according to the image type
>>> +choose_volatile_conf_file () {
>>> +       if ${@base_contains("IMAGE_FEATURES", "x11-sato", "true", 
>>> "false" ,d)}; then
>>> +               if [ -e 
>>> ${IMAGE_ROOTFS}/etc/default/volatiles_stage/volatiles-readonly-sato 
>>> ]; then
>>> +                       cp 
>>> ${IMAGE_ROOTFS}/etc/default/volatiles_stage/volatiles-readonly-sato \
>>> + ${IMAGE_ROOTFS}/etc/default/volatiles/00_core_readonly
>>> +               fi
>>> +       else
>>> +               if [ -e 
>>> ${IMAGE_ROOTFS}/etc/default/volatiles_stage/volatiles-readonly-minimal 
>>> ]; then
>>> +                       cp 
>>> ${IMAGE_ROOTFS}/etc/default/volatiles_stage/volatiles-readonly-minimal 
>>> \
>>> + ${IMAGE_ROOTFS}/etc/default/volatiles/00_core_readonly
>>> +               fi
>>> +       fi
>> Wouldn't be better to have a package which provides the need valatile
>> config? this makes it easy to reuse for other images.
> Yes, you're right.
>
> In fact, I think it should be the initscripts recipe which provides 
> the volatile conf files. Because both populate-volatile.sh and the 
> conf files it uses logically belong to initscripts.
> So I'll remove this function from image.bbclass and choose the correct 
> conf file in the initscripts recipe.
>
After examining it a little more bit, I found out that the conf file has 
to be chosen at rootfs time. It cannot be done by other recipes like 
initscripts because of the sstate-cache.
For example, if we build a minimal image first and then a sato image 
without any change to recipes, the recipes will be skipped by bitbake. 
And as IMAGE_FEATURES are not fully determined until the 
core-image-xxx.bb file is built, using a do_xxx[vardeps] += 
"IMAGE_FEATURES" in other recipes still don't do the work.


> Also, for the purpose of easy use, as you mentioned above, I think we 
> should allow users to use customized conf file if they want to.
> So I want to support customized conf file for volatile storages in 
> initscripts recipe.
>
The same reason stated above, I can't come up with an elegant solution 
to this feature.
Any suggestion?

Cheers,
Chen Qi
> That's all what I've came up with for now.
> I'll send out a patch V6 as soon as possible.
>
> Cheers,
> Chen Qi
>>> +}
>>> +
>>>   # allow openssh accept login with empty password string
>>>   openssh_allow_empty_password () {
>>>          if [ -e ${IMAGE_ROOTFS}${sysconfdir}/ssh/sshd_config ]; then
>>> -- 
>>> 1.7.9.5
>>>
>>>
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>>
>>
>> -- 
>> Otavio Salvador                             O.S. Systems
>> E-mail: otavio@ossystems.com.br  http://www.ossystems.com.br
>> Mobile: +55 53 9981-7854 http://projetos.ossystems.com.br
>>
>>
>
>
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