Hi all, already started the discussion off-list with Pantelis, but it's better done in public: I'm currently exploring ways to make Linux recognize dynamically added virtual hardware when running under the Jailhouse hypervisor [1]. We need to load drivers for inter-partition communication devices that only appear after Jailhouse started (which is done from within Linux, i.e. long after boot) or when a partition was added later on. Probably, we will simply add a virtual PCI host bridge on systems without physical PCI and let the IPC device be explored that way (already works on x86). Still, that leaves us with hotplug and unplug on hypervisor activation and deactivation. Inspired by how FPGA bitstream loaders and the caps/hats for BeagleBones and RasPis work, I thought of using device tree overlays for this. However, it seems there are still some gaps in upstream Linux /wrt overlays. So I would like to find out what already works and what may need further patches. The plan (open for suggestions) is as follows: - have an overlay template for a virtual platform device - compile it into the Jailhouse loader kernel module - adjust key parameters (e.g. register base addresses) after instantiating a device (of_update_property?) - push modified dt into of_overlay_create To my understanding, the last step will trigger driver probing which will cause the device being activated (provided the driver is available, of course). I played with the fragment from Documentation/devicetree/overlay-notes.txt, but already that failed because the in-kernel dtc does not support /plugin/ yet, right? (Why not, btw?) What else do I need to patch/update to make the above work? Or are the simpler ways to achieve what we need? Thanks, Jan [1] https://github.com/siemens/jailhouse -- Siemens AG, Corporate Technology, CT RDA ITP SES-DE Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
