On Fri, Nov 06, 2020 at 07:14:09AM +0000, Matthias Fend wrote: > Hi Ahmad, > > > ________________________________________ > > Von: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> > > Gesendet: Donnerstag, 5. November 2020 21:57 > > An: Matthias Fend; barebox@xxxxxxxxxxxxxxxxxxx > > Betreff: Re: [PATCH] Documentation: state: add a little note about modifying a state variable in the frontend > > > > Hello Matthias, > > > > On 11/5/20 9:16 PM, Matthias Fend wrote: > >> Signed-off-by: Matthias Fend <matthias.fend@xxxxxxxxxxxxxx> > >> --- > >> Documentation/user/state.rst | 1 + > >> 1 file changed, 1 insertion(+) > >> > >> diff --git a/Documentation/user/state.rst b/Documentation/user/state.rst > >> index 78ce24f..d9a8e76 100644 > >> --- a/Documentation/user/state.rst > >> +++ b/Documentation/user/state.rst > >> @@ -689,4 +689,5 @@ be accessed like normal shell variables. The ``state`` command is used > >> to save/restore a *state* variable set to the backend device. > >> > >> After initializing the variable can be accessed with ``$state.foo``. > >> +To modify the value of a state variable use ``nv dev.state.foo=bar``. > > > > That's wrong. You set the value of a state variable with > > state.foo=bar. nv dev.state.state.foo=bar uses the _environment_ to > > save a value to write to state.foo on each boot. This means: > > Thanks for your explanation. Setting a state variable with > 'state.foo=bar' was actually the way I originally expected. > Meanwhile, I figured out why I was struggling using things like that. > All my introduced state variables contained a hyphen in their name. > And I was not able to set a state variable with 'state.foo-bar=baz' while > 'nv dev.state.foo-bar=baz' immediately changed the value of > 'state.foo-bar'. But, as I just learned, with some side effects. > > > > > - If you modify the variable from within barebox, it won't be visible > > in Linux unless you boot barebox once again. > > I could not verify this behavior. When I change a state variable with > 'nv dev.state=foo' and then directly boot into Linux (without booting > barebox again) the 'barebox-state' tool already displays the new value. > > > - If you modify the variable from within Linux, nv.dev.state.state.foo > > would just overwrite the existing value on the next barebox boot. > > That's true, and of course, not desired. > > > > > Generally, you should only need to modify nv variables at runtime > > for debugging. nv.dev is meant for stuff like nv.dev.eth0.ethaddr=XX:XX:XX:XX:XX:XX, > > where you can just hard code a mac address to use, but for state I can't > > think of any good use cases at the moment. > > Right, state, and also it's frontend, does already what it should do and > as expected. > Only the hyphen-obstacle caused troubles. So, maybe there is a trick but the fast fix is to simply > just avoid names that contain hyphens ;) How about converting the hyphens to underscores for the variable names (I mean in code, not in your dts files)? Sascha -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
