[Info-vax] [OT] Raspberry Pi, was: Re: Intel junk...Kernel-memory-leaking Intel processor design flaw forces Linux, Windows redesign

[Simon Clubley]

On 2018-01-11, johnwallace4 at yahoo.co.uk <johnwallace4 at yahoo.co.uk> wrote:
>
> The Raspberry Pi exists because one of the founders,
> Eben Upton, who at the time was teaching at Cambridge 
> University, got seriously concerned about the lack of
> understanding shown by his undergraduate intake. This 
> too is widely documented, e.g. Eben Upton's IET Young 
> Professionals lecture from 2012 (around 45 minutes):
> https://www.youtube.com/watch?v=-P46sRDDONI
>

The Raspberry Pi is ok if you just want to use a supplied version
of Linux and run applications on top of Linux but it is an absolute
disaster area if you want to use it at a lower level with bare metal
programming.

Here's a simple example: feel free to show me the freely downloadable
location for the official datasheets and manuals for the Raspberry Pi's
USB controller.

They are not available unless you are a customer of the vendor who
supplied the USB controller for the Raspberry Pi.

This doesn't even cover all the historical problems with getting data
on the Raspberry Pi's GPU and the last time I checked some of that
information was still closed to the public.

For example, the initial boot sequence on the Raspberry Pi uses a couple
of closed source files which you have to place on the SD card. This is
because the initial boot sequence is controlled by the GPU and not the
ARM MCU.

The ARM MCU is actually held in reset for the first part of the boot
sequence until after the GPU has finished initialising the hardware
and the last time I checked, this boot code was totally opaque; there
was no public documentation available which would allow you to write
your own initial boot code.

So much for the Raspberry Pi being an excellent hobbyist or learning
platform.

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Microsoft: Bringing you 1980s technology to a 21st century world