[conspire] Oh yeah? Raspberry Pi 4 Model B arrives with up to 4GB RAM

[Rick Moen]

Quoting Paul Zander (paulz at ieee.org):

> Depends on what you call a "real computer".  The Raspberry Pi was
> originally intended as an inexpensive way for people, especially high
> school age, to mess around with computer hardware in a way that is
> difficult with a factory assembled computer.

I'm glad you said that, because I was tempted to see if I could re-find
a wonderful recent article describing the history and aims of the RPi
project.  Ah, here it is:
https://www.techrepublic.com/article/inside-the-raspberry-pi-the-story-of-the-35-computer-that-changed-the-world/

When Eben Upton was a director of studies at Cambridge in 2006, he was
shocked by how few people were applying to study computer science, and
realised that what had been missing were the relatively cheap and easily
programmable home computers kids had enjoyed in the 1980s (C64 in the
USA, BBC Micro in the UK), and so set about creating a modern
equivalent.  The aim of a $35 computer was key, that being the price
point where a child wouldn't be afraid to carry it around or connect it
up to other hardware for projects.  It was quite a struggle for some
years to achieve the target retail price.  Broadcom's low-cost BCM2835 SoC
arrived in 2011 and finally was an adequate foundation, but it still
required a lot of work and canny compromises to get the price down from
$110 to $35, finally getting the first production unit out at the end of
February 2012 -- setting the stage for 22 million RPi units produced
since then, and kids lying on living room floors working on their
Raspberry Pis.  Et voila.


Let's talk about what you cannot get with any Raspberry Pi -- even now
that you can get 4GB of RAM -- that by my standards is required for a
'real computer':

1.  Ability to run on RAID1 mirrored storage.  When your storage device
(generally a microSD card) fails, the system goes down and you restore
from backup.[0]

2.  Good mass storage of any kind.  Sorry, but USB is not a reliable
means of storage attachment.

3.  A mainline Linux kernel.  Even after six years of production and
attempts to upstream support code, and convergence on a more-standard
ARMv8 variant starting with the RPi 3, you still really cannot operate
without a downstream, heavily patched raspberrypi kernel.  Mainline
Linux 5.0 is missing (at minimum):

o  CPU frequency driver
o  device tree overlay support, and knowledge of the per-RPi device tree[1]
o  GPIO support
o  several major proprietary firmware BLOBs.[2]

Tellingly, the rpi-open-firmware project to replace those proprietary
BLOBs came to a half, at least for now, in the middle of 2017, because
the lead developer became too disgusted with certain hideous design
compromises built into the hardware by Broadcom.  See:
https://github.com/christinaa/rpi-open-firmware/issues/37
Someone there asked the incumbent developer what single-board computer
he's leaning towards, and he replied:  'Virtually any AArch64 SoC that's
not made by Broadcom with a GPU and doesn't lock down TrustZone and
leaves OTP [RM: the One-Time Programmable (OTP) memory block]
unprogrammed for most part.  Look into sunxi.'

Interesting comparison table on Wikipedia, showing which single-board
computers run on mainline Linux kernels:
https://en.wikipedia.org/wiki/Comparison_of_single-board_computers#Operating_system

The picture's a little grim.  Only these qualify:

phyBOARD-Wega
phyBOARD-Mira
Embedded Now Piconium
BeagleBone Black
Arrow Electronics Dragonboard 410c
DreamPlug
Gizmo Board
Inforce IFC6410
Intel Galileo Gen 2
MinnowBoard
PC Engines APU
ESPRESSObin

Of those, the PC Engines APU and MinnowBoard products line are the most
real-computer-compliant, which is not surprising since they use low-power
AMD and Intel Atom x86_64 CPUs, respectively.  The Inforce IFC6410 isn't
bad, either.

Which gets me back to my main point which is that you still aren't able
to do Linux on aarch64 without grievous compromises including a bunch of
proprietary software and non-standard kenels.  You still need x86_64,
and personally I still think it's still a mistake to go with ARM for
anything that matters.  (That was the case a few years ago when I last
seriously considered ARM, and I'm sad to see it's still the case now.)

But admittedly, none of the less-compromised alternatives has come to
market at a $35 price point.


[0] You could probably RAID1 a pair of USB devices, but really now.
[1] https://www.raspberrypi.org/documentation/configuration/device-tree.md
[2] https://github.com/raspberrypi/firmware/tree/master/boot