About the TCp/ip stack in RTEMS

Gene Smith gds at chartertn.net
Thu Sep 11 19:11:51 UTC 2008

Ralf Corsepius wrote:
> On Wed, 2008-09-10 at 10:58 +0800, PowerMan wrote:
>> I am doing a project which uses the NXP LPC2300.
>> The NXP LPC2300 is based on arm7-tdmi & have a internal ethernet 
>> controller. But the internal sdam is only 32KB.
>> The FreeBSD tcp/ip stack in RTEMS seems too large for such kind of
>> MCU ( with internal ethernet controller and small sram, another
>> example is at91sam7x128) .
>> Why not substitute lwip for it in the source tree?
> First of all lwip would have to prove
> a) functional equivalence to the BSD stack
> Though the BSD stack in RTEMS is only a partial port of the original BSD
> stack and gradually diverging from the BSD stack due to the fact it
> receives too little attention, it should not be too difficult to add
> further features, the original BSD-stack supports.

I assume you are saying rtems port of BSD stack "receives too little 
attention," not the free BSD stack itself? I am curious if any security 
or performance enhancements have been made since it was ported to RTEMS. 
(Looking through the CVS I don't see a lot, but only looked at few files.)

> b) stability.
> The BSD is widely used.
> c) portability, standard conformance.
> A non-portable "toy stack" not complying to any standard doesn't help
> anybody.
> That said, I don't see any reason to replace the BSD stack. If at all,
> an alternative stack may be added in parallel to the BSD stack. Should
> this stack once prove its viability, we could start discussing to
> abandon the BSD stack.

Yes, I agree, don't think RTEMS should "abandon" the FreeBSD stack. Just 
provide hooks to use a more compact stack as an alternative for small 
systems or systems needing better security or performance. I thought I 
read something on the list about doing this possibly through a "Summer 
of Code" project to include a lighter stack alternative.

It would be nice if one could link in any comm stack to RTEMS such as 
the well maintained (according to marketing blurbs), also BSD derived 
but non-free Interniche stack (Granted, source could not be distributed 
and have rtems remain free).

> Ralf
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