On Wed, 7 Jun 2023 at 09:34, Ilias Apalodimas <ilias.apalodimas@xxxxxxxxxx> wrote: > > 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". > Forgot to attach the link... apologies for the noise. [0] https://lore.kernel.org/all/CAC_iWjLOhUvp5ggCCkHN5MRNfB_h6FZ2Z14yrtR3aqGn0Ovxig@xxxxxxxxxxxxxx/ > Thanks > /Ilias > > > > Jan > > > > -- > > Siemens AG, Technology > > Competence Center Embedded Linux > >
