[Sussex] Sky boxen / Embeded LINUX and NT

[Geoff Teale]

Morning chaps,

How was last night?  Sorry I couldn't be there.

At the end of this e-mail is a question, if you know something about how
LINUX works at the low-level please feel free to skip there, what follows is
a discription of a worrying in embedded space..

Lots of discussion going on here about sky boxen.  I don't have one but
Jon's experience is in line with most people I've met.  Sky boxes crash, and
crash on a reasonably regular basis.  

I have some experience with embedded systems (principally on QNX RtP, but
also BeIA (now the core of the forthcoming Palm OS6(?)), VxWorks, WindowsCE
and NT Embedded) and I have to say that they seem to be exceptionally
unstable.

Now I know all of us are used to software crashing.  Yes, even in LINUX (I
may be a fanatic but I try to be an honest one!).  My experience with
windows is that server "services" tend to be less reliable than on UNIX, but
most userland apps are reasonably stable these days - infact my one big
bugbear on my desktop at work is IE6 which is a roach motel on a massive
scale - but the most likely cause of a crash is _still_ windows memory
handling.  We have a number of 2Ghz P4 Dell boxes here (including the
machine on which I am now typing), each has 512MB of DDR RAM.  Under Windows
2000 these machines _all_ crash during or following periods of high memory
consumption (mine most commonly does it during interactive debugging or
compiling - which is annoying in VB and can waste hours in VC++).

According to the Dell people (who spent days working on this for us and a
number of other clients) this is a problem with with Windows 2000 that
happens on machines that match the following conditions:

(RAM <= 32MB  && (RAM >= 384MB && RAM <=1GB )) && 
	((CPU->Type = PentiumIV) && CPU->Speed > 1.4Ghz))

... under pressure from Dell Microsoft have admitted this is a fault and
apparantly they are working to have a fix in the next release of Windows
XP(!!!!).

Anyhow, what does any of this have to do with Sky boxes ?

Well... I have a nice "dropout" advert that came in a US copy of DDJ (Doctor
Dobbs Journal of Calisthenics and Orthodontia - Running Light without
Overbyte) which states proudly that Sky Television supply a UI for digital
television to manufacturers on the Microsoft NT Embedded platform.  They
proudly claim 99.999% uptime.  Note - the memory management in the NT
embedded kernel is that same as in Win2000 and XP (I believe that NT
Embedded has recently been updated and rebranded as XP embedded - though
this may be WinCE which is as different product).

Straw poll - think of all the embedded devices you own.  VCR, washing
machine, fridge, television, microwave, etc etc.  How many of those need to
be rebooted on a regular basis ?

Let me guess: none ?

So what's the difference?  Easy, the OS.  Microsoft are a relatively new
player in the embedded OS market they fall into a fairly modern embedded OS
design camp.  Microsoft take a large desktop OS and cut it down to fit in an
embedded device (Microsoft's idea of an embedded device has about the same
spec as brand new PC did 3 years ago..).  Most other embedded OS's take the
opposite approach.  They are designed to provide a minimal environment in
very low resource environment and then scale up to bigger implementations.

Because of these design differences pure embedded OS's tend to have had a
lot of time spent on getting the low level stuf right and very little time
spent on providing high level functionality or development environments.

A lot of new projects are turning to Windows because:

1/ It make providing rich functionality easy (ie. multi-media or web
browsing).

2/ It's easy to find C/C++ developers with VC++ experience, plus you don't
have to pay them as much.

3/ A large portion of the public will, given the choice, buy a Microsoft
powered device rather than any other option because they place _trust_ in
Microsoft. (look at the PDA market to see this phenomenon).

.. people are trading stability for functionality.  Windows as an OS is
fundementally unsuitable for this kind of application and your Sky Boxes are
living proof.

How is all of this is relavant to LINUX?  Well, LINUX is also making big
inroads in embedded space.  Like Windows it's a desktop/server OS that's
making it's way into embedded systems as the processing power and memory
specs increase rapidly.  It's seen as a platform, like windows, which can
bring all it's desktop functionality and it's community of (cheap)
developers to embedded development.

============
The Question
=============

How can we be sure that LINUX in embedded space isn't a lame duck just like
Windows?


-- 
GJT
geoff.teale at claybrook.co.uk
 


The above information is confidential to the addressee and may be privileged.  Unauthorised access and use is prohibited.
 
Internet communications are not secure and therefore this Company does not accept legal responsibility for the contents of this message.
 
If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it, is prohibited and may be unlawful.
 
Claybrook Computing Limited is a subsidiary of Claybrook Computing (Holdings) Limited
Registered Office: Abbey House. 282 Farnborough Road, Farnborough, Hampshire GU14 7NJ
Registered in England and Wales No 1287205
 
A Hogg Robinson plc company