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 _______________________________________________ firstname.lastname@example.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"