On Tue, Nov 5, 2013 at 12:41 PM, Pantelis Antoniou <panto@xxxxxxxxxxxxxxxxxxxxxxx> wrote: > Add a runtime interface to /proc to enable generic device tree overlay > usage. > > Two new /proc files are added: > > /proc/device-tree-overlay & /proc/device-tree-overlay-status I think we really want all this to live under sysfs. Grant did patches to move /proc/device-tree to /sys, but it never went upstream: v2: https://lkml.org/lkml/2013/3/21/215 v1: https://lkml.org/lkml/2013/3/20/311 > /proc/device-tree-overlay accepts a stream of a device tree objects and > applies it to the running kernel's device tree. > > $ cat ~/BB-UART2-00A0.dtbo >device-tree-overlay > overlay_proc_release: Applied #2 overlay segments @0 > > /proc/device-tree-overlay-status displays the the overlays added using > the /proc interface > > $ cat device-tree-overlay-status > 0: 861 bytes BB-UART2:00A0 Is the size useful information? > > The format of the status line is > <ID>: <SIZE> bytes <part-number>:<version> > > <ID> is the id of the overlay > <SIZE> is the size of the overlay in bytes > <part-number>, <version> are (optional) root level properties of the DTBO > > You can remove an overlay by echoing the <ID> number of the overlay > precedded with a '-' > > So > $ echo "-0" >device-tree-overlay-status > > Removes the overlay. This interface seems racy. Could the id change on you between reading the status and echoing to remove the overlay? I would rather see a file created for each overlay and simply echo 0 or "remove" to remove the overlay. Or possibly it needs to be a directory per overlay with several files for info and control. This would be more inline with typical sysfs design. Rob -- 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
