Another Dave  wrote:
> Yes. I understand the Linux boot process. I'm simply quoting Andrew
> Tanenbaum, the author and still developer of Minix, who said that he
> chose the beaglebone for ARM development because it was more open source
> than the Pi. I therefore expressed a wish, and I'm not the first, that
> more of the Pi's drivers were open in the spirit of the subject of this
> thread.
> If you think he was wrong and that you can help, then his email is
>
> astanenbaum@gmail.com
>
> In addition I'm not sure that it's in the spirit of Minix that there's a
> whole load of abstraction to a closed blob of any part of the kernel
> processes.

Fair enough, if you can only support one platform then you have to pick one.
But the Pi GPU firmware is essentially similar to a PC BIOS - and people
don't insist they can't use a PC unless the BIOS is open source.

I should be clearer about this: there is a high chance that almost every
hardware component of any complexity you talk to has a processor of some
kind inside running software - that you don't get the source to.  That
includes the BBB.  A lot of that software is in ROM that you can't change.
You communicate via a defined API - maybe that API uses registers over MMIO
or I2C or whatever, but it's still an API.  So it's not fair to single out
the Pi with its GPU, which is essentially no different.

Now, there are projects for making fully open source SoCs - eg SiFive and
lowRISC, and they (will be) great for learning platforms.  Likewise there
are open source FPGA systems.  However today you can't buy a fully open source
SoC of the Pi class.

But do I need the source code for (eg) my touch screen controller?
If it gives me X, Y and number of fingers, that's probably all I need it to
do.  I'm not going to be booting Linux on it or mining bitcoins.

Parts of the Pi hardware have open-source drivers but not open-source
documentation - which is a different problem, and I can understand that
makes it less attractive.  It is, unfortunately, a problem shared with a lot
of other SoCs (TI are one of the better vendors in terms of documentation).
If that's the reason then it's understandable.

Theo

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