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TCPIP stack size




On Wed, 7 Jul 1999, Trevor Higgins wrote:

> Can anyone give some data on size of BSD tcpip stack in code bytes and
> memory bytes.
> I want to get a feel for what are the minimum resources likely to 
> be consumed to see if it is likely to fit in available ram/rom.
> (prefereble less than 128k of each).

There has been no effort to trim the BSD stack memory requirements in
anyway.  The aim all along has been to leave the code intact as much as
possible to ease incorporation of bug fixes and updates from the original
source.  

I would only suggest that (1) if there is a reasonable subset, AND (2) you
can't get to that subset because RTEMS specific support code is
referencing code other than that subset, THEN we can look at how to break
the dependency.

Breaking dependency chains in the rest of the RTEMS source code has
resulted in files being broken apart so referencing one symbol does not
pull in another unwanted function.  Since the bulk of the TCP/IP stack is
BSD code with minimal modifications, this approach will not be possible.

This is not to say the stack size can not be reduced -- only that there
are special considerations.

> (I laughed at the README comment that suggested changing the heap from 
> 256K to 512K when using tcpip, as I dont expect to be using more than 
> about 20K of heap all up.)

My understanding is that this is primarily for the data buffers to hold
incoming and outgoing data.  Lowering this increases the likelihood of
running out of buffers.  

Someone else probably needs to throw in a comment here.

--joel
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
   Support Available             (256) 722-9985