[squeak-dev] seL4 Microkernel: How small can the shim be?

David T. Lewis lewis at mail.msen.com
Sun Feb 28 14:31:18 UTC 2021


Hi Lian,

I'm not sure if you are aware, but Tim is one of the original core
VM developers and is the author of the RISC OS VM for Squeak. Here
are a few links of interest:

  http://squeakvm.org/riscos/

  http://www.rowledge.org/tim/squeak/

  http://squeakvm.org/cgi-bin/viewvc.cgi/squeak/trunk/platforms/RiscOS/

  http://source.squeak.org/VMMaker


In addition to the official VM releases that Tim provided, the source
code is all still on line in a Subversion repository at squeakvm.org
(platform source code) and in the VMMaker repository at source.squeak.org
(for the VM code written in Smalltalk).

Dave


On Sun, Feb 28, 2021 at 02:11:43PM +0100, Liam Proven wrote:
> On Sat, 27 Feb 2021 at 20:42, tim Rowledge <tim at rowledge.org> wrote:
> >
> > Also - if you're interested in minimal OS with easy low-level access you could do worse than investigating RISC OS. Get a Pi, download the package from riscos direct )https://www.riscosdev.com/direct/) and play.
> 
> I am well aware of RISC OS. I distributed some fractal generators for
> RISC OS back in the 1980s. :-) I have a RPi 3B+ running RISC OS Direct
> sitting right next to me.
> 
> In fact, I have already been trying to explain some of the limitations
> of RISC OS to the people running the Cloverleaf kickstarter campaign.
> 
> I wrote some of it up in a blog post, here:
> https://liam-on-linux.livejournal.com/73983.html
> 
> This generated a bit of discussion on HackerNews, but as usual, lots
> of heat but little light.
> https://news.ycombinator.com/item?id=24735766
> 
> I still play around with RISC OS today. The reasons that I do not
> think it is a suitable candidate for new efforts are:
> ??? It is not a clean simple design: it is an old, complex one;
> ??? It is mostly ARM assembler and not even slightly portable; even
> moving it to new ARM hardware is hard;
> ??? It is technically very limited, with little memory protection, very
> limited CLI-only pre-emptive multitasking, no support for threads or
> SMP;
> ??? It is 32-bit only and the only realistic way of doing a 64-bit
> version will be using some kind of VM or emulation
> 
> Other interesting lightweight vintage OSes which are now FOSS:
> ??? Atari ST TOS/Mint: https://aranym.github.io/afros.html
> ??? A relatively early version of Sinclair QDOS, Minerva:
> https://github.com/janbredenbeek/Minerva4Q68
> ??? The final version of the Sinclair OS, rewritten for Atari hardware,
> SMSQ/e: http://www.wlenerz.com/smsqe/
> ??? A FOSS re-implementation of the original Amiga OS:
> https://aros.sourceforge.io/
> 
> But all of these are compromised, limited designs, hard to port, hard
> or impossible to modernise while retaining any compatibility.
> 
> Really, seriously, this talk was based on _over_ a decade of research
> and study. My choices were not casual ones or lightly considered! :-)
> 
> I was not merely looking for a lightweight OS. I had a demanding list
> of criteria.
> 
> I looked for:
> ??? a clean, simple OS, with SMP support, that supported pre-emption,
> memory management etc.
> ??? in a type-safe language, with a native-object-code compiler ??? not
> JITTed, not using a VM or runtime
> ??? and a readable language, not something far outside the Algol family
> of imperative HLLs
> ??? that was portable across different architectures
> ??? that was FOSS and could be forked
> ??? that was documented and had a user community who knew it
> ??? that can be built with FOSS tools (which RISC OS fails, for instance)
> ??? which is or was used by non-specialists for general purpose computing
> ??? which can usefully access the Internet
> ??? which runs on commodity hardware
> ??? which does not have a strongly filesystem-centric design that would
> not fit a PMEM-only computer (i.e. not an xNix)
> 
> If anyone else has any candidates that meet all of these, I would very
> much like to know. It took a lot of searching and I don't know
> anything else that ticks all the boxes.
> 
> -- 
> Liam Proven ??? Profile: https://about.me/liamproven
> Email: lproven at cix.co.uk ??? gMail/gTalk/gHangouts: lproven at gmail.com
> Twitter/Facebook/LinkedIn/Flickr: lproven ??? Skype: liamproven
> UK: +44 7939-087884 ??? ??R (+ WhatsApp/Telegram/Signal): +420 702 829 053
> 


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