[asterisk-dev] Warning and/or question (Zaptel MMX)

Tzafrir Cohen tzafrir.cohen at xorcom.com
Mon Aug 27 23:54:41 CDT 2007


Long ago, in a far away galaxy, on Tue, Sep 12, 2006 at 09:50:17AM +0100, 
Steve Davies wrote:

> Hi,
> Firstly, a note of caution for those compiling MMX into Zaptel... I
> use an EPIA processor, which may be part of the problem, but enabling
> the Zaptel MMX code caused sufficient corruption that it affected
> other userspace processes! I suddenly started getting page-errors in a
> web application, and this only happened when Asterisk was up and
> running, using Zaptel.

Do you happen to remember which CPU exactly it was? Is it a C2 (e.g:
Nehemia, Esther)? I believe those should have a better MMX
implementation than some of the older VIA CPUs (e.g: Ezra).

> Recompile Zaptel with No-MMX, and all is well again.
> Secondly a question - I notice the "CLOBBER_MMX" macro in the Zaptel
> code. This is not documented anywhere... Might it help with the
> corruption?

I also heard from jsmith yesterday on #asterisk-dev that 4 or 5 years
ago he had bad luck using CONFIG_ZAPTEL_MMX with on Athlon and Athlon XP
CPUs then.

I also noticed that all echo cancellers allocate memory (the
echo_can_state) in GFP_KERNEL. Isn't the echo canceller used in an 
interrut context?

Then there's also ECHO_CAN_FP . IS it something that an echo canceller
using the floating point unit must set? Is it actually used?
(I don't see mec3-float.h referenced anywhere).

               Tzafrir Cohen       
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