Is it possible to run a read-only fs without IMAGE_FEATURE = "read-only-rootfs"

Is it possible to run a read-only fs without IMAGE_FEATURE = "read-only-rootfs"

[Beek, Léon van de]

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Dear all,

Currently I have created an image which upon boot mounts my rootfs as readonly in an overlay with my data partition. I set out to change the FS type of my rootfs to something that is actuall read-only like squashfs, however I am getting a kernel panic whenever I boot saying:

"Not syncing: vfs: Unable to mount root fs on unknown-blick(179,2)"

The steps I took to convert to a read-only rootfs:

  *   Change -fstype in .wks file to squashfs
  *   Changed IMAGE_FSTYPE= "squashfs wic.bz2", in local.conf, however I do not believe this is necessary actually

Are there steps I am missing? I believe that IMAGE_FEATURE = "read-only-rootfs" should not be necessary as I am mounting the rootfs in an overlay before starting /sbin/init , but I might be wrong.

Kind regards,

Léon van de Beek

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Re: [yocto] Is it possible to run a read-only fs without IMAGE_FEATURE = "read-only-rootfs"

[Quentin Schulz]

Hi Léon,

On December 13, 2021 3:40:05 PM GMT+01:00, "Beek, Léon van de" <l.v.d.beek@student.tue.nl> wrote:
>Dear all,
>
>Currently I have created an image which upon boot mounts my rootfs as readonly in an overlay with my data partition. I set out to change the FS type of my rootfs to something that is actuall read-only like squashfs, however I am getting a kernel panic whenever I boot saying:
>
>"Not syncing: vfs: Unable to mount root fs on unknown-blick(179,2)"
>
>The steps I took to convert to a read-only rootfs:
>
>  *   Change -fstype in .wks file to squashfs
>  *   Changed IMAGE_FSTYPE= "squashfs wic.bz2", in local.conf, however I do not believe this is necessary actually
>

Did you check that your kernel actually supports squashfs as rootfs? There is a Kconfig option for it IIRC.

>Are there steps I am missing? I believe that IMAGE_FEATURE = "read-only-rootfs" should not be necessary as I am mounting the rootfs in an overlay before starting /sbin/init , but I might be wrong.
>

Since it's an image feature, it's not going to impact anything outside of the image recipe but I don't know exactly what this is doing from memory.

Cheers,
Quentin

>Kind regards,
>
>Léon van de Beek