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 ;) Thanks, ~Matthias > >> ``state -s`` stores the *state* to the backend device. >> > > -- > Pengutronix e.K. | | > Steuerwalder Str. 21 | https://eur04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.pengutronix.de%2F&data=04%7C01%7CMatthias.Fend%40wolfvision.net%7C264e50c95bc64c72ac6c08d882229f76%7Ce94ec9da9183471e83b351baa8eb804f%7C0%7C0%7C637402432501383585%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=dKzSGReGqacxdJcKZ6eldNiulqmv6%2B8qzQxhijoRbC4%3D&reserved=0 | > 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
