[yocto] [meta-raspberrypi] Read-Only RootFS is not read only

[Andrei Gherzan]

On Mon, Aug 5, 2013 at 1:12 PM, Andrei Gherzan <andrei at gherzan.ro> wrote:

>
>
>
> On Mon, Aug 5, 2013 at 2:51 AM, Rich Bayliss <richbayliss at gmail.com>wrote:
>
>> Sorry Paul - I am new to all this. I have checked and I am using Poky
>> (1.4)
>>
>> Rich
>>
>> On 4 August 2013 23:35, Paul Eggleton <paul.eggleton at linux.intel.com>
>> wrote:
>> > On Sunday 04 August 2013 01:27:01 Rich Bayliss wrote:
>> >> On 2 August 2013 13:47, Paul Eggleton <paul.eggleton at linux.intel.com>
>> wrote:
>> >> > On Tuesday 30 July 2013 11:43:43 Rich Bayliss wrote:
>> >> >> I am trying to build for Raspberry Pi including "read-only-rootfs"
>> in
>> >> >> my image features. My aim is to have my SD Card read-only and at
>> some
>> >> >> point add a read-write overlay to certain directories. This should
>> >> >> enable my system to boot fresh each time, and have some persistent
>> >> >> storage for user files etc.
>> >> >>
>> >> >> However, after building my image I can SSH into the system and issue
>> >> >> "touch test" to create a file in my home directory, then after a
>> >> >> reboot it is still there. That isn't very read-only :)
>> >> >>
>> >> >> Am I missing something, or is this working incorrectly?
>> >> >
>> >> > It sounds like it's working incorrectly. Since meta-raspberrypi
>> constructs
>> >> > the SD card image using its own custom class I wonder if it has
>> anything
>> >> > to do with that. Andrei, do you know anything about this?
>> >> >
>> >> > BTW, are you using sysvinit or systemd in this image?
>> >>
>> >> I am using the standard sysvinit/systemd - I haven't specified either,
>> >> so whichever is default.
>> >
>> > Except the default depends upon what DISTRO you are using. Which DISTRO
>> are
>> > you using - "poky" or something else?
>> >
>> > Cheers,
>> > Paul
>> >
>> > --
>> >
>> > Paul Eggleton
>> > Intel Open Source Technology Centre
>>
>
> Will check on this tomorrow. I've been on the roads these days.
>

Summary:
I managed to find the root of the problem. We used to have an old fstab
which i'm going to get rid of with a patch today - as the default one is
working ok and fixes this issue.

The problem was related to:
tmpfs                /run                 tmpfs
 mode=0755,nodev,nosuid,strictatime 0  0
We didn't have this specified in our fstab and would make udevd to keep the
device busy => remount fail.

Thank you for reporting this. And sorry for being late with investigation -
managed to get some vacation :)

-- 
*Andrei Gherzan*
m: +40.744.478.414 |  f: +40.31.816.28.12
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