[OE-core] [PATCH] wic: Prevent duplicate entries on fstab

[Otavio Salvador]

On Mon, Mar 6, 2017 at 4:07 PM, Ed Bartosh <ed.bartosh at linux.intel.com> wrote:
> On Mon, Mar 06, 2017 at 03:48:00PM -0300, Fabio Berton wrote:
>> Hi Ed,
>>
>> The main motivation to my patch is prevent to duplicate entries. For
>> example, if I add to my fstab line:
>>
>> LABEL=data           /data                auto defaults              0  1
>>
>> and add to wsk file:
>>
>> part /data --ondisk mmcblk0 --fstype=ext4 --label data --align 8192
>> --size 500M --extra-space 0
>>
>> Final fstab will have two entries for /data.
> This can be easily avoided if you remove leading slash:
> part data --ondisk mmcblk0 --fstype=ext4 --label data --align 8192 --size 500M --extra-space 0

HACK ALERT!

>> In most Linux distros mount /boot partition, if we have kernel image
>> or boot script to update we need to mount /boot partition. Why the
>> reason to not mount /boot?
>>
> The code that skips / and /boot was brought to wic codebase more than 4
> years ago: https://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=75c143a7aef46ecea07cf33edd2b1a0192e10149
>
> I don't know exact reason to be honest. However, I think we need to be careful with this
> kind of legacy. It doesn't mean we shouldn't remove it, but it should
> not be done as a side effect of the patch addressing absolutely
> different issue, I believe.

While discussing this with Fabio here, at O.S. Systems, we ended
agreeing that wic touching the fstab is wrong. The fstab should be
prepare as part of the image and not mangled during the disk
generation.

The mangled fstab is disastrous if someone uses an image upgrade. The
generated tarball or filesystem WILL NOT be the same running on the
device as wic will add entries.

-- 
Otavio Salvador                             O.S. Systems
http://www.ossystems.com.br        http://code.ossystems.com.br
Mobile: +55 (53) 9981-7854            Mobile: +1 (347) 903-9750