Hi Frank, On Fri, Oct 19, 2018 at 2:06 AM Frank Rowand <frowand.list@xxxxxxxxx> wrote: > On 10/18/18 12:32, Rob Herring wrote: > > On Tue, Oct 16, 2018 at 05:34:26PM -0700, frowand.list@xxxxxxxxx wrote: > >> 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 (1) dynamic devicetree modifications and (2) 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. > > > > I'd prefer to see some sort of information on overlays exported and user > > space can check if that changed. IIRC, Pantelis had a series to do that > > along with a kill switch to prevent further modifications. At least some > > of that series only had minor issues to fix. > > The kill switch addresses a different concern, which was from the security > community. The kill switch is on my todo list. > > I don't remember exactly what info the overlay information export patch > provided. I'll have to go find it and re-read it. I'm still forward porting the overlay configfs interface, cfr. https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git/log/?h=topic/renesas-overlays E.g. after loading r8a7791-koelsch-exio-b-scifa3.dtbo, it changes like: --- tree /sys/firmware/devicetree old 2018-10-19 08:49:24.073441000 +0200 +++ tree /sys/firmware/devicetree new 2018-10-19 08:49:33.173397000 +0200 @@ -1237,6 +1237,11 @@ │ │ │ │ ├── groups │ │ │ │ ├── name │ │ │ │ └── phandle +│ │ │ ├── scifa3 +│ │ │ │ ├── function +│ │ │ │ ├── groups +│ │ │ │ ├── name +│ │ │ │ └── phandle │ │ │ ├── scif_clk │ │ │ │ ├── function │ │ │ │ ├── groups @@ -1510,6 +1515,8 @@ │ │ │ ├── interrupts │ │ │ ├── name │ │ │ ├── phandle +│ │ │ ├── pinctrl-0 +│ │ │ ├── pinctrl-names │ │ │ ├── power-domains │ │ │ ├── reg │ │ │ ├── resets @@ -2277,6 +2284,7 @@ │ │ ├── scifa1 │ │ ├── scifa2 │ │ ├── scifa3 +│ │ ├── scifa3_pins │ │ ├── scifa4 │ │ ├── scifa5 │ │ ├── scifb0 The above hunks are for /sys/firmware/devicetree/base/. @@ -2778,6 +2786,14 @@ │ │ └── target │ └── __symbols__ │ └── target + ├── 2 + │ ├── can_remove + │ ├── fragment@0 + │ │ └── target + │ ├── fragment@1 + │ │ └── target + │ └── __symbols__ + │ └── target └── enable The above hunk is for /sys/firmware/devicetree/overlays/ # ls -l /sys/firmware/devicetree/overlays/ total 0 drwxr-xr-x 6 root root 0 okt 19 08:49 1 drwxr-xr-x 5 root root 0 okt 19 08:49 2 -rw-r--r-- 1 root root 4096 okt 19 08:49 enable 1 is from the DT unit tests, 2 is from r8a7791-koelsch-exio-b-scifa3.dtbo, enable is the kill switch. Note that after removing overlay 2, and loading a new overlay, the new one is again called number 2. But the subdir date is newer. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
