On 10/15/18 17:35, valdis.kletnieks@xxxxxx wrote: > On Mon, 15 Oct 2018 17:27:01 -0700, frowand.list@xxxxxxxxx said: >> From: Frank Rowand <frank.rowand@xxxxxxxx> >> >> When an overlay is applied or removed, the live devicetree visible in >> /proc/device-tree/, aka /sys/firmware/devicetree/base/, reflects the >> changes. There is no method for user space to determine whether the >> live devicetree was modified by overlay actions. >> >> Provide a sysfs file, /sys/firmware/devicetree/tree_version, to allow >> user space to determine if the live devicetree has remained unchanged >> while a series of one or more accesses of /proc/device-tree/ occur. >> >> The use of both dynamic devicetree modifications and overlay apply and >> removal are not supported during the same boot cycle. Thus non-overlay >> dynamic modifications are not reflected in the value of tree_version. > > Is there an easy way from userspace to detect "yes/no dynamic modifications > have been done since boot"? > Unfortunately not. I considered adding detecting dynamic modifications in another patch, making this a two patch series, but that feature will be much more intrusive than detecting modifications made by overlays. I may add that feature in the future, but not anytime soon. If you want to understand a little bit about why dynamic modifications occur, please see my reply to Geert in the thread about version 1 of this patch.
