Re: [ECOS] Footprint

[Grant Edwards <grante at visi dot com>]

On Thu, Aug 03, 2000 at 03:16:20PM -0600, Shaun Jackman wrote:

> eCos being as configurable as it is, I'm sure there's no one good example of
> what kind of footprint to expect.
> Nonetheless, to the closest power of 2, I was wondering how much memory I
> should budget for the OS and TCP/IP stack. Note: I have dead-slow flash
> which will have to be copied into main memory, so there's no need to
> differentiate between r/o and r/w (although if you do have the figures
> handy, it would be interesting).
> So, for an ARM target incorporating TCP/IP via ethernet, how much RAM is
> needed to run a basic demo? (a tiny httpd for example)

I'm running an ARM7 system with TCP/IP, one Ethernet driver,
and the serial driver.  If you substitute a simple http server
for the custom-protocol server I'm using you should end up with
something on the same order of magnitude.

I'd say a good minimum would be 512KB of RAM.  My ARM7 system
looks rougly like:

     TCP/IP  text+data = 100K    (incl Ethernet driver)
     TCP/IP  buffers   = 128K
     Kernel  text+data =  48K    (incl Serial driver)
     App     text+data =  48K
     Total bss         = 128K    (incl stacks, serial buffers, Ethernet buffers)

So, depending on the http server size (which would be in the
App category above) you might be able to get by w/ 512KB, but
if I were you, I'd be ready to bump it up to 1M.  That would
allow you to increase the buffer space for the TCP/IP stack to
the default 256KB.

-- 
Grant Edwards
grante@visi.com