[uClinux-dev] some guidelines

Thomas Andrews tandrews at mindspring.co.za
Fri Nov 9 01:54:56 EST 2001


David McCullough wrote:

> Jivin Kendrick G. Hamilton lays it down ...
> 
>>On Thu, 8 Nov 2001, Thomas Andrews wrote:
>>
>>
>>>Hi,
>>>
>>>I've just joined the list so please forgive me if this question has been
>>>answered a thousand times.
>>>
>>>I'd like to know if using uClinux on a QUICC with 32MB of RAM and say 2MB of
>>>flash makes sense on a board that's used as a kind of a "gateway" device.
>>>
>>You have enough memory to run uClinux. We are running it on 2.5MB of ram
>>and 1 MB of flash.
>>
> 
> I think most people would agree that 32Mb is enough RAM :-)
> The siz eof flash required is dependant on the size and number of apps you
> load.
> 
> 
>>>The protocols I want to support would be SNMP v3, ftp (for upgrades) SSH if
>>>
> 
> SNMP is quite big (230K binary,  600K+ runtime)
> 
> 
>>>it makes sense, and perhaps RIP2/OSPF or maybe STP. Initially I would put
>>>
> 
> If you go for something like Zebra then is it also quite large:
> 
> 	RIP   - 167K binary
> 	OSPF  - 270K binary
> 	ZEBRA - 124K binary
> 
> I think it's about 700K ripd+zebra runtime.
> 
> So it won't take long to use up 2Mb of flash if you are putting in a lot of
> large (in the embedded sense) apps.  Although you look fairly safe with
> your requirements so far.
> 
> With 32Mb of RAM you can always store everything compressed in ROM to buy
> more space and just expand it into RAM.
> 
> 
>>>two of these units together to make an ethernet bridge, but later maybe have
>>>some routing capability. (connected via some totally proprietary hardware)
>>>
>>>I'm sure this brief description is too broad and vague, but what I'm really
>>>trying to find out is what the problems are in developing such an
>>>application. I've chosen linux because the device is likely to be
>>>unprotected by firewalls, so I want something I know and trust.
>>>
>>>I'm about to build uClinux for the existing hardware we have, just to get a
>>>feel for things, but I have no idea where I'm likely to get stuck in the
>>>future. What are the main difficulties and limitations I will encounter ?
>>>
> 
> The best way to find out is play with it :-)
> 
> Cheers,
> Davidm
> 
> 

Thanks David, that's really useful info.

If a package (say net-snmp v3) needed to be ported, what typically are the 
difficulties that one experiences. Is it that the applications make library 
calls that are not supported, or is it just a matter of "tweaking" until it 
compiles ok. (Loading at run-time is a mystery to me, but I'll get to that).

Many thanks,
Thomas

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