RTEMS on tiny microcontroller

[Sebastian Huber]

Benoit Camus wrote:
> Hello all,
> 
> I read a lot of thing about memory usage on mailing list and have to say 
> i'm a bit in doubt about it.
> 
> Here is the available memory i have: 256ko Flash /  64ko RAM ( could be 
> 512/128 but i'd really like to avoid it ).
> The microcontroller i use is an arm: at91sam7x.
> 
> The question is what i need ?
> Of course the kernel itself, ideally with the posix interface and the 
> Ethernet stack (the FreeBSD one).
> I guess this last point is the worst. and i don't need all of the stack 
> just: TCP, UDP layers ( 2-3 connection for each ), Broadcast and 
> Multicast capability and that's it.

Here is the memory layout for an application with telnet and FTP services on an
LPC2478 (ARM Thumb):

Idx Name          Size      VMA       LMA       File off  Algn
  0 .start        00000120  00000000  00000000  000000d4  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  1 .vector       000005c0  40000000  40000000  00061bd4  2**0
                  ALLOC
  2 .text         00048540  00000120  00000120  000001f4  2**2
                  CONTENTS, ALLOC, LOAD, CODE
  3 .rodata       0000b380  00048660  00048660  00048734  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  4 .data         0000e120  a0400000  000539e0  00053ab4  2**2
                  CONTENTS, ALLOC, LOAD, DATA
  5 .bss          00007880  a040e120  a040e120  00061be0  2**5
                  ALLOC

> 
> Considering all this needs, do you think it will fit in memory ? Is 
> there any options fine tune the system and  drop down it size ?

As far as I know the TCP/IP stack is monolithic in RTEMS.  You may have a look
at http://www.rtems.com/wiki/index.php/Open_Projects#LWIP.

> 
> A last question to help me doing some tests, where could i find a 
> ready-to-use arm-rtems compiler ?

http://www.rtems.com/wiki/index.php/RTEMS_Development_Hosts

> 
> Thanks in adavance.
> B. Camus
> 


-- 
Sebastian Huber, Embedded Brains GmbH

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