Hi Jan, [...] > >>>> > > ... > >>> > >>> I think we have a probe ordering issue with this driver: > >>> efivarfs_fill_super() may be called before the TEE bus was probed, thus > >>> with the default efivar ops still registered. And that means > >>> efivar_supports_writes() will return false, and the fs declares itself > >>> as readonly. I've seen systemd mounting it r/o initialling, and you need > >>> to remount the fs to enable writability. > >>> > >>> Is there anything that could be done to re-order things reliably, probe > >>> the tee bus earlier etc.? > >> > >> This driver has a dependency on user-space daemon: tee-supplicant to > >> be running for RPMB access. So once you start that daemon the > >> corresponding device will be enumerated on the TEE bus and this driver > >> probe will be invoked. So I would suggest you to load this daemon very > >> early in the boot process or better to make it a part of initramfs. > >> > > > > That is not the point, really. > > > > If this dependency exists, the code should be aware of that, and made > > to work correctly in spite of it. Requiring a module to be part of > > initramfs is not a reasonable fix. > > In fact, I've tested a non-modularized build as well, just to exclude > that issue. The daemon dependency is more likely the problem here. > > > > > IIUC, this also means that the efivar ops are updated while there is > > already a client. This seems less than ideal as well As Sumit pointed out, the 'device' won't be available from OP-TEE until the supplicant is up and running and as a result, the module _probe() function won't run. Unfortunately, this isn't something we can avoid since the supplicant is responsible for the RPMB writes. The only thing I can think of is moving parts of the supplicant to the kernel and wiring up the RPC calls for reading/writing data to the eMMC subsystem. There was another discussion here [0] requesting the same thing for different reasons. But unless I am missing something this won't solve the problem completely either. You still have a timing dependency of "when did the RT callbacks change" -- "when was my efivarfs mounted". Thanks /Ilias > > Jan > > -- > Siemens AG, Technology > Competence Center Embedded Linux >
