barebox state w/ qemu

[Wes Chow]

Ahmad,

> Normally, the barebox device tree already describes the state and
> environment, but Qemu is a special case, because the device tree is
> not compiled into barebox, but supplied by the virtual machine.
>
> Thus this overlay to add some barebox specific information. As this
> should happen very early, so that the environment can take effect early
> on, the overlays aren't applied dynamically in this case, but compiled-in.

Thanks, that's very helpful. I'm starting to understand but I'm not
quite there yet...

> Because that flash is a fixed part of the virt machine, you should
> already have functional state:
>
>   barebox at ARM QEMU virt64:/ state
>   registered state instances:
>   state                (backend: raw, path: /dev/nor0.barebox-state)
>
> Is this not the case and if not, what errors did you get?

I do have the same thing. If I'm reading the docs correctly though I
should be able to modify state with the nv command, right? This
doesn't seem to persist the foo variable:

 barebox at ARM QEMU virt64:/ state
 registered state instances:
 state                (backend: raw, path: /dev/nor0.barebox-state)
 barebox at ARM QEMU virt64:/ nv foo=bar
 nv variable modified, will save nv variables on shutdown
 barebox at ARM QEMU virt64:/ nv
   allow_color: true
   autoboot_timeout: 3
   foo: bar
   user: none
 barebox at ARM QEMU virt64:/ poweroff

When I restart Qemu the "foo" variable goes away. And actually, every
time I start Qemu I get this message:

 state state.of: Fresh state detected, continuing with defaults

Do I need to specify a flash device when starting Qemu? I'm running
this (taken from the docs):

 qemu-system-aarch64 -m 2048M -cpu cortex-a57 -machine virt -display
none -serial stdio -kernel ./images/barebox-dt-2nd.img

... but I'm guessing I'm missing a pflash argument. I've been trying
various incantations but haven't been able to get Qemu to boot
successfully if I supply a `-drive if=pflash,...`.

Thanks,
Wes