Re: For the AdaOS folks

["Warren W. Gay VE3WWG" <ve3wwg@NoSpam.cogeco.ca>]

Dmitry A. Kazakov wrote:
> On Thu, 30 Dec 2004 08:58:23 -0500, Warren W. Gay VE3WWG wrote:
>>Nick Roberts wrote:
>>>However, I intend to design the microkernel so that it compromises on
>>>minimality (unlike some other microkernel designs)
>>
>>Yes. Mach is too fat. They shouldn't have included device drivers
>>for example.
> 
> Implementations of or the generic interface for? I think the latter would
> be a mistake. DOS->Windows tried this path. MS consistently refused to
> specify device classes other than hard drive and keyboard.

I'm not sure exactly what you're supporting here (clearly not M$), but
IMHO, the device driver(s) can be written on top of the microkernel,
and need to be inside it. This also helps to keep the mk small.

>>>to achieve reasonable
>>>efficiency (whilst removing much of unnecessary detritus that bogged down
>>>experimental microkernels), and I intend to ensure that administrative
>>>division of the network is fully supported, as well as network partioning
>>>robustness (if some workstations go down, the rest still work).
>>
>>I wonder if networking really belongs in the microkernel. This is
>>necessary for example if like Mach, you say that ports can speak
>>to other Mach machines on the network/cluster.
> 
> That is an interesting question. I think that the kernel should be able to
> tunnel its requests through higher order protocols.

Yes, they can be provided on top of the microkernel, as you seem to
be suggesting.

>>However, you might want to take the tact that networking is done
>>outside of the microkernel. This way, in situations where you don't
>>want networking (embedded systems), it need not be there.
> 
> There are lot of embedded systems which need networking, starting from
> boards interconnected through dual ported RAM, to various sensors and
> actors devices attached via Ethernet.

I am not disputing that. But that is different than saying every
embedded device needs it. So if you want to save some memory, then
the first thing that can be dumped (if the option exists) is
networking if you don't require it. If it is included in a
given mk, it should be optional.

However, IMHO, the microkernel should be small as possible, and
leave networking up to the modules outside of it. After all, some may
perfer an IPv6 only version of networking for example (in light
of China's recent network announcment). In the end, I don't want
to be "stuck" with what a brand of microkernel gives me. Just
give me the basics and let me decide what is included.

>>I always get scoffed at for suggesting this, and I have no love for M$,
>>but the one idea they have had, which is useful, is the registry.
> 
> It might look attractive and is definitely better than Unix chaos, 

So we agree that it is an improvement over little text files that
you must parse/edit etc..

> but the
> concept of registry is not good. Try to reformat an Windows box and restore
> all settings of say MS VC back.

You base your registry criticisms upon M$ _implementation_ of
a registry. But consider this:

If each registry item were a file (on a RieserFS so there is little
or no waste), then you can backup, secure and restore settings
just like any other file. You can do so with all of those familiar
tools, including tar and cpio.

> Registry makes program's settings a property of the local machine or user.
> The problem is that tree view. It should be at least relational. But better
> would to have different views.

I don't believe it need be treated any differently than a file
system. To support a registry on the RieserFS for example, one
merely need to add a nice programming API to make it easier for
programs to query and set values. You can still use links/symlinks
(if you must) etc.
--
Warren W. Gay VE3WWG
http://home.cogeco.ca/~ve3wwg