[yocto] rootfs mounted read-only on Live USB (x86-64)

[Dan O'Donovan]

On 06/03/2016 10:54 AM, Oleksandr Poznyak wrote:
> Hi,
Hi Oleksandr
> Check if "read-only-rootfs" feature is added to any of these variables either in your local.conf or your image bitbake recipe:
>
> Something like that:
>
> IMAGE_FEATURES = "read-only-rootfs"
>
> EXTRA_IMAGE_FEATURES += "read-only-rootfs"
Thanks for your suggestion.  I didn't find "read-only-rootfs" specified in the IMAGE_FEATURES in local.conf or elsewhere.  I suspect it might be a different issue because it only affects the live-boot of the .iso image.  If I install the .hddimage directly to the storage device instead, then it boots fine and the rootfs is read/write.

[update]
It looks like the problem was indeed the lack of aufs.
I added this in conf/local.conf
    DISTRO_FEATURES_append = " aufs"
and this in the kernel recipe
    KERNEL_FEATURES_append += "${@bb.utils.contains('DISTRO_FEATURES', 'aufs', ' features/aufs/aufs-enable.scc', '', d)}"
and now the live USB image boots correctly with a read-write filesystem.

Considering that the default images built for a generic x86-64 machine include a live-boot image (.iso) which is effectively broken, I assume the aufs feature (or another solution for the live-boot use case) should really be added by default for those builds as well.
>
> Thanks,
> Oleksandr Poznyak!
>
> On Fri, Jun 3, 2016 at 12:06 PM, Dan O'Donovan <dan at emutex.com <mailto:dan at emutex.com>> wrote:
>
>     Hi all
>
>     Has anyone else noticed that the root file-system appears to be mounted read-only when booting a Live USB image from Yocto 2.1.
>
>     This is on a sato build from the krogoth branch of poky and meta-intel, for a generic x86-64 machine (4.4 kernel).
>
>     I'm transferring the resulting .iso image to a usb stick using 'dd', and then picking the 'boot' option at startup.
>
>     As well as a bunch of errors about the read-only filesystem (e.g. failing to create files in /var and other locations), the desktop UI fails to load.
>
>     This worked fine with Yocto 2.0.
>
>     I have a hunch that it might be caused by a lack of aufs support.  Is it possible that aufs patches were omitted from the x86 kernels in Yocto 2.1?
>
>     Thanks,
>     -Dan
>
>     P.S. It works fine if I just install it directly, or if I use the .hddimg, instead of trying to boot the live image from the .iso.
>     --
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