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

[johnwallace4 at yahoo.co.uk]

On Thursday, 11 January 2018 13:29:48 UTC, Simon Clubley  wrote:
> 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


Pi isn't a panacea. Needs vary, so do solutions. 

Pi is a better teaching platform for many purposes than 
most of the alternatives, for loads of reasons that have 
been done to death elsewhere. It's not even all about
the products - there is a momentum and a community behind
Pi of a kind which hasn't been seen for a while, and that
in itself adds something.

Some folks even find Pi products are an OK deployment 
platform for some kinds of requirements, e.g. where
there is need for simple low cost readily available 
physical IO (stuff which is readily available and 
affordable in the Pi community and likely to stay so,
not buy ten milliona and we'll tell you about it, but 
if you want another ten million in a year it'll likely 
have changed by then). 

Needs vary, so do solutions. 

Having some understanding of what goes on beyond the
mouse can sometimes help people in understanding the 
difference between appropriate and inappropriate - as
you've just demonstrated. What looks good on paper
may come with hidden snags, as I found when I did my
first ARM-based comms gateway project ages ago.

Based on StrongARM running MontaVista Linux, in an 
industrial box maybe A5 size, it seemed to fit the bill 
perfectly. Until we wanted to put our modified kernel
into flash where it could autoboot. The device vendor
didn't want to document how to do that, and there were
some challenges with the local IT department allowing
non-Wintel kit onto the corporate LAN.

Just the kind of thing that Pi might come up against,
except that sensible people nowadays will at least have
heard of Pi but may not have heard of MCUs or Beagles 
or PCI/104 or whatever.

TLDR: Pi's good at a lot of things, and it's cheap
and fashionable. Just because something's fashionable 
doesn't mean it fits everywhere, does it.