FreeBSD-like linux distro?

[Frank Shute]

On Wed, Jun 11, 2008 at 09:30:17PM +0300, Heikki Suonsivu wrote:
>
> Frank Shute wrote:
> >On Wed, Jun 11, 2008 at 05:06:49PM +0300, Heikki Suonsivu wrote:
> >>Oops, sorry, I was not specific enough:
> >>
> >>FreeBSD 4 or older NetBSD are no go:
> >>
> >>The computer I am doing this is not old, it is otherwise brand new, but 
> >>it uses an embedded cpu, a 486 clone as SoC without math.  See 
> >>www.compactpc.com.tw, eBOX 2300SX.  It is very low cost, runs on about 
> >>3W of power with CF card as mass memory, 128M, 3 USB2, serials, sound, 
> >>etc, it has VESA form factor so you can attach it behind many LCD 
> >>displays, etc. They have beefier models, but this one is cheapest and 
> >>uses least power, latter of which is the more critical requirement for us.
> >>
> >>We would like to use it for certain control applications.  Linux works, 
> >>has been tested, but requires patches (turn math emulation on, add 
> >>support for built-in ethernet, bug workaround).
> >
> >I don't know if this machine is going to be sited on an insecure
> >network or not. If it is, then you'll probably be using ssh. Without
> >a math co-proc to do the crypto, it will be horrendous. I don't even
> >know if ssh would work with an architecture without a maths unit.
> 
> You apparently do not use the source :), go and grep double and float 
> from some of the most common programs you use (games, scientific stuff 
> and crappy UI code excused).

No, I don't use the source :)

I kind of assumed "It must do a lot with numbers, so it will run like
a dog without a co-processor".

> 
> > If it can't work with ssh, then you might be restricting your market.
> 
> ssh does not use any floating point for any crypto algorithm.  Oh, 
> openssh does use doubles, it prints some ratios in some places, such as 
> how many percent of something has been transferred.  It seems to be 
> stirring random numbers as floating point non-exactness does is not a 
> bother there, but that is not used past session init.  There is no 
> human-noticeable effect on normal ssh use.

It was explained to me (off-list) that co-processors work on floats
not ints.

> 
> I was one of the first guinea pigs for original ssh.  We did have plenty 
> of non-math cpus back then, and I did run ssh on non-fpu hardware until 
> two years ago.  We did run backups and configuration tasks over ssh on 
> number of non-fpu computers acting as routers and other servers those 
> days.  Today's games might be different, but that is not what we do on 
> these embedded computers...

I didn't think you'd be having the odd game of Quake on one of your
boxes. But think of it as an added feature! :)

>
> >I think you are punishing yourself unneccesarily by going with a
> >processor without maths. You restrict the software (both OS &
> >application) you can run.
> 
> Applications cannot tell the difference between math emulation and 
> hardware from anything else than performance, so there is no code 
> difference in application layer, and kernel does not do fp at all, other 
> than trapping fpu instructions and emulating them on non-fpu hardware. 
> Kernel itself does not do fp math.
> 
> I do not quite understand where this fear of non-fpu came from, as it 
> made no practical difference just few years ago for anything but 
> scientists in labs and intensive cad/graphics work.  In particular I do 
> not understand why people have an idea that everything uses floating 
> point.  Very few programs do heavy math processing, most common use is 
> to double divide two longs to print out some statistics when program ends.

I used to do a lot of CAD and buying a machine without a co-processor
was considered madness. That's where my prejudice comes from.

> 
> >>The problem with is that while FreeBSD 4 seemed to boot on it, it did 
> >>not recognize any peripherals as they are new.  Old OS's are not really 
> >>what we want, this is not one-off but volume product, it will be 
> >>internet-connected so we need bugfixes and we need support for latest 
> >>chipsets on 802.11 cards etc.
> >>
> >>There is another similar CPU, even slower and less power consuming, I do 
> >>not remember the part number, I think it was about 100 MHz 486 without 
> >>math as well.  This was some manufacturer of microcontrollers.
> >
> >Can't you find a manufacturer that makes something similar with a DX
> >instead? Or can you email this company and ask them how much it would
> >cost to run off X units with a 486DX rather than SX?
> 
> This is not 486, it is System-on-Chip thing.  There are couple of very 
> cheap SoCs, which do not have math, but performance is otherwise 
> adequate for most applications.  They are much faster than 486SX, by 
> 5-10 times factor, so they are becoming popular on embedded devices.

I was referring to the 100MHz 486 you looked at.

I'd still get an fpu so you can install a largely unpatched OS of your
choice even if the fpu is redundant beyond installing the OS.

I guess you looked at the Soekris stuff and discounted it. Shame,
because a lot of folks find them useful with *BSD.

> 
> >>Heikki
> 

Regards,

-- 

 Frank 


 Contact info: http://www.shute.org.uk/misc/contact.html