From: Paul Gortmaker <[email protected]> Adding to your local.conf right out of the gate:
EXTRA_IMAGE_FEATURES = "read-only-rootfs" while you are trying to sort out other things can be just another complication to an already steep learning curve. For example, I found simply enabling this with systemd caused: systemd[1]: Failed to fork off sandboxing environment for executing generators: Protocol error [!!!!!!] Failed to start up manager. systemd[1]: Freezing execution. While I'd like to get to the root cause of that, it doesn't change that things boot fine w/o adding to EXTRA_IMAGE_FEATURES, even though the rootfs is still read-only courtesy of dm-verity. Reword things so as to make it clear it isn't strictly a hard requirement and hence can be delayed as people work through their implementation. Signed-off-by: Paul Gortmaker <[email protected]> --- docs/dm-verity.txt | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/docs/dm-verity.txt b/docs/dm-verity.txt index ce1839520982..c2dce739790d 100644 --- a/docs/dm-verity.txt +++ b/docs/dm-verity.txt @@ -53,11 +53,18 @@ conf/local.conf and conf/bblayers.conf from the oe-init-build-env Firstly, you need the meta-security layer to conf/bblayers.conf along with the dependencies it has -- see the top level meta-security README for that. -Next, assuming you'll be using dm-verity for validation of your rootfs, -you'll need to enable read-only rootfs support in your local.conf with: +Note that if you are using dm-verity for your rootfs, then it enforces a +read-only mount right at the kernel level, so be prepared for issues such +as failed creation of temporary files and similar. + +Yocto does support additional checks and changes via setting: EXTRA_IMAGE_FEATURES = "read-only-rootfs" +...but since read-only is enforced at the kernel level already, using +this feature isn't a hard requirement. It may be best to delay/defer +making use of this until after you've established basic booting. + For more details, see the associated documentation: https://docs.yoctoproject.org/dev/dev-manual/read-only-rootfs.html -- 2.40.0
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