Re: [PATCH] image: remove / entry from fstab template

[Florian Bezdeka <florian.bezdeka@siemens.com>]

On 06.01.23 05:58, Moessbauer, Felix (T CED INW-CN) wrote:
> On Thu, 2023-01-05 at 14:08 +0100, Florian Bezdeka wrote:
>> On Tue, 2022-10-04 at 13:46 +0200, Henning Schild wrote:
>>> An fstab entry for / should usually not be required. It just makes
>>> a
>>> rootfs less portable (USB vs. NFS, vs. SSD). The kernel is the one
>>> that should know which fs to mount and how. That is done via a
>>> bootloader.
>>>
>>> Should additional mount options be needed for a concrete image, an
>>> imager like wic might add an entry. i.e. for adding fspassno or
>>> x-systemd.growfs
>>>
>>> So to make the rootfs more generic and to allow imagers to add
>>> their
>>> individual / lines, instead of having to modify an existing one,
>>> remove
>>> the line from the template.
>>>
>>> Signed-off-by: Henning Schild <henning.schild@siemens.com>
>>
>> Hi all,
>>
>> FYI: While trying to update Isar in one layer using LAVA tests we
>> recognized that there is now a breaking change:
>>
>> Previously the rootfs was mounted rw on ext4 images because we had
>> the
>> / line in /etc/fstab, triggering systemd-remount logic.
>>
>> As the entry for the root (/) has been removed in /etc/fstab
>> remounting
>> does no longer happen. This breaks several LAVA tests here as well as
>> start-qemu scripts. Adding "rw" to the kernel cmdline would be one
>> option but we have a lot of LAVA job descriptions and even more
>> start-
>> qemu scripts in downstream layers.
>>
>> Felix already send out patches to OE (open embedded) to address that
>> in
>> wic. Necessary Isar patches (wic update, ...) will follow soon.
>> Thanks
>> a lot Felix for taking over.
> 
> Hi Devs,
> 
> let me add some additional information:
> 
> - in OE, the fstab in the rootfs contains the / entry
> - we added a patch to OE to let WIC handle the root partition, but this
> had been reverted because it led to duplicated entries (which break
> systemd-remount)
> 
> By that, we are no longer in sync with OE. Also considering the revert
> of the WIC patch, this shows that OE want to keep the / entry in the
> rootfs fstab for the meantime.
> 
> Instead of discussing fundamental aspects (like if the line should be
> in the rootfs fstab or not) I vote for just integrating the
> deduplication logic in WIC and re-add the / entry in the rootfs fstab.
> This brings us in sync with OE again and from then on we can discuss
> how the general design should look like.

+1. Let's fix the current bug (duplicate entry for / in /etc/fstab)
first. Anything else can be addressed afterwards - if necessary at all.

> 
> Felix
> 
>>
>> Best regards,
>> Florian
>>
>