This layer holds fixes for read-only-rootfs support that were needed by Mentor Graphics Corporation. The biggest change was handling read-only-rootfs for systemd images.
We provide a read_only_rootfs_systemd.bbclass, which ensures that the fstab
in the image gets switched to 'ro', the way it does with sysvinit images.
We also provide a volatile-binds recipe, which generates service files for bind mounts to ensure that certain areas are writable, much like the sysvinit read-only-rootfs hook does. This is data driven, however, and also makes /media writable by default. Note that changes written to these areas will not persist, as the bind mounts utilize /var/volatile, which is tmpfs.
The final piece in here is recipe bbappends to fix behavior regarding read-only-rootfs, and thus far we've only needed one: lighttpd.
This layer depends on:
URI: git://git.openembedded.org/openembedded-core Branch: master
URL: https://github.com/MentorEmbedded/meta-ro-rootfs
To contribute to this layer, please fork and submit pull requests to the above repository with github, or open issues for any bugs you find, or feature requests you have.
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Add this layer to
BBLAYERSin bblayers.conf -
If building systemd images, ensure that / is mounted r/o when using read-only-rootfs by adding this to local.conf, or your distro .conf:
INHERIT += "read_only_rootfs_systemd"
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Enable read-only-rootfs for your images, by adding this to local.conf:
EXTRA_IMAGE_FEATURES += "read-only-rootfs"
If the default writable paths (/var/lib, /home/root, /media, and /etc/resolv.conf) are insufficient, you can add additional bind mounts for files or directories. Examples:
VOLATILE_BINDS_append = "/var/volatile/www /www\n"
VOLATILE_BINDS_append = "/var/volatile/rsyncd.conf /etc/rsyncd.conf\n"