New RISCV board (cartesi-machine)

[Marcelo Politzer]

On Wed, Sep 15, 2021 at 6:17 PM Ahmad Fatoum <a.fatoum at pengutronix.de> wrote:
>
> Hello Marcelo,
>
> On 15.09.21 22:30, Marcelo Politzer wrote:
> > Hi, I'm new to barebox
> >
> > I'm currently porting barebox to a riscv board (cartesi-machine).
>
> Oh, looks interesting! What SoC does it use?

It uses SOC_VIRT. It is an emulator to be precise, we use it for
verifiable computations.
It is pretty easy to try it out (there is a docker image for it):
https://www.cartesi.io/en/docs/machine/host/overview/

>
> > I got it mostly working:
> > - new serial: serial_sbi.c and
>
> Keep in mind that newer SBI versions deprecate
> sbi_console_getchar() and sbi_console_putchar() with no replacement.
>
> But if your board's firmware provides it, there is no issue with
> adding a driver for it.

That is what the emulator implements for now.
I have to admit that a virtio system would be cool, maybe in the future.

>
> > - ext4 filesystem with mtdram
> >
> > 1) What I am still trying to figure out is how to customize `env` correctly.
> > I got it to build and appear based on the docs [1], [2],
>
> Those look ok. I assume you have
>
> defaultenv_append_directory(defaultenv_cartesi); in your board code?

yes

>
> > however the only way I found around [3] was to replace `bin/init` with
> > this[4] layout.
>
> After drivers probe, barebox invokes init to source init scripts and
> do the countdown and such. This is written in C, but you can override
> it with an /env/bin/init shell script, which is what you did here.
>
> I would not recommend this. Drop /env/bin/init and use the same C init
> nearly everyone else does. You can still customize it via the
> /env/init/ scripts
>
> > Is there a recommended way to go about this?
>
> You need to set boot.default, e.g.
>
> echo 'cartesi net' > defaultenv-cartesi/nv/boot.default
>
> Which would try cartesi first and then net if the first one failed.

That worked great.
Looks a lot cleaner now.

>
> > 2) I also would like clarification on the upstreaming process, is it
> > PR based, patches on this list?
>
> Patches to the mailing list are the usual way of contributing.

OK, I'll clean this up and send it as two patches:
- serial_sbi
- cartesi (board)

>
> Cheers,
> Ahmad
>
> >
> > best,
> > Marcelo
> >
> >
> > [1] Makefile:
> > ```
> > bbenv-$(CONFIG_BOARD_CARTESI) += defaultenv-cartesi
> > ```
> >
> > [2] arch/riscv/boards/cartesi:
> > ```
> > defaultenv-cartesi
> > ├── boot
> > │   └── cartesi
> > ├── init
> > │   ├── automount
> > │   └── ps1
> > └── nv
> >     ├── allow_color
> >     ├── autoboot_timeout
> >     └── user
> > ```
> >
> > [3]
> > ```
> > Hit m for menu or any to stop autoboot:    0
> > Booting entry 'net'
> > ```
> >
> > [4]
> > ```
> > defaultenv-cartesi
> > ├── bin
> > │   └── init
> > └── boot
> >     └── cartesi
> > ```
> >
> > _______________________________________________
> > barebox mailing list
> > barebox at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/barebox
> >
>
>
> --
> 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 |