Re: 2.6.16 serious consequences / GPL_EXPORT_SYMBOL / USB drivers of major vendor excluded

[Sasha Khapyorsky <sashakh@gmail.com>]

On 12:02 Sun 19 Feb     , Steven Rostedt wrote:
> 
> > > differences between AVM and other devices and the difficulties regarding a
> > > possible move towards user mode.
> > >
> > > The user space does not ensure the reliability of time critical analog
> > > services like Fax G3 or analog modem emulations. This quality of service
> > > can only be guaranteed within the kernel space.
> >
> > Soft modems may work pretty well in userspace - slmodem is example.
> >
> > Real-time requirement for V.34 is 40ms response time and only once during
> > the session when echo canceller parameters are negotiatiated (so you may
> > decrease "buffer size" before and increase after - there are enouph
> > silence places for such manipulations). Fax itself does not require any
> > "realtime" AFAIK, other place is almost unused today V.32 - 26ms, also
> > for echo canceller setup.
> >
> 
> Disclaimer:  This is in no way a push to get the -rt patch into mainline
> at the moment.  The patch is still young and is not ready yet.

Hmm, it was not about -rt patch - 40 millisecond response time is
realistic for userspace even without -rt patch. There is no guarantee,
but in practice this may work very well and keep low percents of failures
(much lower than permitted by standards).

Sasha.