Megaco stack

Matthias Lang <>
Thu Aug 26 11:12:19 CEST 2004


Guillermo Fernandez Castellanos writes:

 > I had a look to the Erlan FAQ, and finded the following references:
 > 
 > 5.5 How do I write an Erlang system that fits on a floppy?
 > http://www.sics.se/~joe/sae.html
 > Unfortunatelly this distribution does not give a lot of details about 
 > the libraries that it includes, and Megaco does not seem to be one of them.

As far as I know, nobody uses SAE for a production system. There's no
showstopper preventing you from doing that, but you will be a
pioneer. That means you will spend time solving problems that you
wouldn't have to deal with if you'd chosen a more mainstream approach.

 > 8.9. Is Erlang small enough for embedded systems?
 > """It is reasonably straightforward to fit Erlang itself into 2Mbyte of 
 > persistant storage"""
 > """ This can be automated by editing otp.mk and adding +compressed 
 > +no_debug_info to the erlang compiler options and then rebuilding all 
 > the libraries."""
 > unfortunatelly I did not find it that straightforward nor was able to 
 > find the opt.mk file...

"Straightforward" in the context of "embedded systems" means that
someone with a reasonable amount of Erlang experience and a reasonable
amount of embedded system experience can do it without having to write
new code or do surgery on existing code. But messing with makefiles
and playing detective with grep is par for the course.

In answer to your specific problem: I can think of two reasons why
you can't find "otp.mk". Firstly, you misspelt it. Secondly, maybe
you're looking for it in a source tree which hasn't been configured,
i.e. you haven't run "configure" first. "configure" creates it from
"otp.mk.in".

Aside: In 2001, some embedded hardware I work with included an Erlang
system stripped down to 2Mbyte. Now, it's grown to 3MByte. The growth
is mostly due to ERTS doubling in size from R7B to R9C (compiled
without HIPE). I haven't investigated what exactly has grown.

 > I then thought about simply stripping (deleting...) the non used OTP 
 > modules (applications) from the compiled Erlang distribution. But 
 > something tells me it's not a good idea...

That's exactly how I cut down Erlang for a widely used embedded
system. Although that system can be used as a media gateway, it
doesn't have MEGACO.

Matthias



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