[ltp] MWave-Linux-Petition

[Valery Trifonov]

On Thu, 9 Sep 1999 09:19:54 -0700 (PDT) Paul Rubin <phr@netcom.com> wrote:

> I'd really prefer to sign a separate petition to get rid of the mwave
> instead of inflicting it on linux.

Maybe, but I believe the rest of your post makes an excellent point in favor
of Mwave support for Linux.

> The "great wheel of karma" theory
> is very cute but in reality, as processors get cheaper, it's proven
> effective to use more and more of them rather than putting more
> functions in software.  A modern Thinkpad probably has at least 10
> processors (besides the main cpu, the keyboard controller has its own
> processor, the battery pack has one, the disk and cd-rom drives each
> have at least one, etc.).  There are also things like the serial
> UART's which perform functions that in the old days might have been
> done by software.  They are practically cpu's in their own right and I
> think they may actually be implemented that way.  It would be
> ridiculous to hair up the Linux kernel with those functions in the
> name of some abstract notion of technical elegance.  Don't overlook
> the motives of some of the advocates of using the main cpu for
> these things (i.e. Intel Native Signal Processing initiative).
> It's financially great for Intel if you use a $500 Pentium-VII 
> to run that DSL modem in software, but it's simply more cost effective
> and bug resistant to use a $5 embedded DSP.

Correct me if I'm wrong, but that's just what "Mwave" is -- an
embedded DSP board, based on MDSP 3780. The load on the main CPU using
a Mwave modem is about the same as with a conventional modem. OTOH a
Winmodem ((tm) Lucent) is a glorified ADC/DAC, and the CPU is forced to
do a lot of work in hard real time to make it sing.

The problem as I understand it is that since the Mwave DSP board is
multi-purpose (modem/fax/voice but also a MIDI synth for example), IBM
have decided to have each application download its own DSP software
instead of storing it on a flash ROM as in other DSP-based modems.  So
somebody has to write the modem software (well, that seems done
already since the modem works under Windows) and download it to the
DSP. But the DSP runs a small real-time operating system to coordinate
its many tasks, so the driver must follow some non-trivial protocol
when talking to it. IBM don't want to tell us what the protocol is and
what DSP software (from their Windows distribution) to download. I
think it's less likely but it may also be that this software does not
provide 100% emulation of a modem on a serial port.

Well, this may be a bit oversimplified. :-)

Valery