[asterisk-dev] GSM trunks & Dahdi - New funcionality Request for discussion

[Artem Makhutov]

Hi,

On Fri, Nov 20, 2009 at 12:32:40PM +0100, Kai Hoerner wrote:
> Artem Makhutov wrote:
> > Also the debugging, installation and so on would be more complicated.
> > You will have to recompile the kernel modules on a kernel update and so on...
> >   
> Debugging would be more complicated, agreed.
> You will have to recompile the kernel modules on kernel update anyways,
> since they are still needed even if AT translation is done in user
> space. So i don't see any difference here.

At least the Huawei sticks have in kernel drivers. So this don't have
to be recompiled seperate on kernel updates.

> > I don't see any reasons to put this into kernel space.
> >   
> Probably a great benefit of this approach is that new device drivers can
> be created and installed without even touching the AT standard command
> library. Device specific code would be handled in one single place,
> which seems logical to me. Also, this would allow vendor's to create
> closed source drivers (we dont want them, but sometimes it's better than
> nothing).

Sure, but you can also create a standard library which can load closed
source modules.

If a user space application crashes you just need to restart it.
If a kernel module crashes then you might need to restart the whole server...

> By the way, i do not see the need of this "standard AT" library anyways.
> couldn't you exchange just signals between userspace and the driver
> modules? the driver itself should convert the "standard gsm signalling"
> into which AT commands ever are needed to do actually execute the
> signalling on the device.
> (just thinking too)

Yes, this is what we have to do:

Create a standard library with all the required signalling stuff and so on.
This standard library can load additional "translation" modules for the
specific devices which translate the "standard signalling" into device
specific commands.

To achieve this we need to define the things that should be handled by the
standard library.

Things like:
Dial a number
Hang up
Answer
Ring
Switch SIM card
Enter PIN code
Send/Receive SMS
Monitor signal strength
Monitor GSM network
Send/Receive FAX
Increase Volume
Send DTMF
CUSD messages
....

Regards, Artem