[uClinux-dev] uclinux-voip gateway

박 찬택 urinara1 at hotmail.com
Fri Nov 23 03:01:39 EST 2001


Hi,

I have just ported Quicknet's LineJack device driver to NET+Lx 
successfully.
1) NET+40 Rev4
2) NET+Lx 0.99.0 (uClinux kernel 2.0.38.1pre7arm)
3) Glue board to attach ISA card to NET+ARM board's expansion slot.
4) isapnp-arm7tdmi (device driver for ISA PNP)
5) ixj-arm7tdmi    (device driver for Quicknet's LineJack)
6) ixjsdk-arm7tdmi (sample apps for Quicknet's LineJack)
7) glibc-2.1.3 for NET+Lx (for posix thread library)
8) vocal-20010711-arm7tdmi (Vovida's SIP and MGCP protocol stack & apps)

There were one big problem and two little problems.
Please refer to the following link.
http://www.uclinux.org/pub/uClinux/archive/4547.html
I have spent many times to resolve them for about 3 months.

A big problem was NET+Lx arm-gcc compiler's bug.
There are several threads.
http://www.uclinux.org/pub/uClinux/archive/5144.html
http://www.uclinux.org/pub/uClinux/archive/5026.html
http://www.uclinux.org/pub/uClinux/archive/0740.html
It did not appear, when I used Aplio's compiler or when I used option 
-fpic.
So, my solution(?) is to use Aplio's 20000519 distribution for kernel 
(includes device driver) compiling and to use NET+Lx's 20000110 
distribution to compile user space apps.
:) I'm a stupid about compiler.

First little problem was that I had to port 2.2/2.4 device driver to 2.0 
kernel.
Quicknet's LineJack device driver (ixj.c) supports 2.2 and 2.4 kernels 
only.
Rubini's book (Linux Device Drivers, 2nd) was very helpful to me. Thanks to 
Alessandro Rubini.

Second little problem was in device driver.
There was critical race condition within implementation of blocking I/O 
when use interruptible_sleep_on() in read and write operation.
It may lock up a device in the worst case.
It is described in Rubini's book, "Going to Sleep without Races".

Currently, ixj and tpjack in ixjsdk are working good over 24-hours.
(There is another problem. It is that the delay of voice between two 
endpoints increases with the lapse of time.)
I already ported and tested MGCP gateway(with null driver) of VOCAL to 
NET+Lx 3 months ago.
I'm attempting to merge them just now.
Thanks to Joe deBlaquiere, Tom Walsh, David McCullough and all other 
person.


CT Park,

Best Regards.


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