[lwip-users] Minimum for TFTP client

[Mathias Zenger]

I would like to write an ethernet boot loader for my embedded system. A
small TFTP client shall be part of the bootloader. The client shall be based
on the raw API (code size is critical). Can somebody explain me which bare
parts from lwIP (or perhaps uIP) I shall use to get a basic TFTP
communication working? I guess I would need ARP, IP and UDP (but which
files?). Would be great if somebody even could provide a functional example.

Regards,
Mathias

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[Simon Goldschmidt]

"Mathias Zenger" wrote:
> I would like to write an ethernet boot loader for my embedded system. A
> small TFTP client shall be part of the bootloader. The client shall be
> based
> on the raw API (code size is critical). Can somebody explain me which bare
> parts from lwIP (or perhaps uIP) I shall use to get a basic TFTP
> communication working? I guess I would need ARP, IP and UDP (but which
> files?). Would be great if somebody even could provide a functional
> example.

I would recommend to compile all files and use lwipopts.h to strip down code size (most of the files are then automatically left out through #if's).

Then, copy opt.h and define everything to 0 you don't need. I think there are some recommendations regarding size in the lwip wiki.
You should set NO_SYS to 1 (unless there's an OS in your bootloader), and you can at least turn off (LWIP_-) TCP, ICMP, IP_FRAG/_REASS, RAW, NETCONN and SOCKET. Regarding RAM usage (not code size), you will want to configure the MEM/MEMP settings as low as possible, although you need to tweak this after your application is finished.

Oh, and I guess you'd nee DHCP, too, for your client to get an IP address. The current code doesn't allow it, but I have a change in preparation that parses the bootloader file returned by the DHCP server.

And last but not least, I'd greatly appreciate if you could share the code with us: I'd like to add such a boot-client to the dhcp client code...

Simon
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[Madhusudan Bhat]

Hi,

 

Is there built in tftpclient in the lwip? or you are writing tftpclient or integrating tftp client code using raw API given? I think dhcp code is part of the core, but tftp is not there right?

 

thanks,

MB.

On Tue, Jan 19, 2010 at 3:46 PM, Simon Goldschmidt <gold...@gmx.de> wrote:

"Mathias Zenger" wrote:
> I would like to write an ethernet boot loader for my embedded system. A
> small TFTP client shall be part of the bootloader. The client shall be
> based
> on the raw API (code size is critical). Can somebody explain me which bare
> parts from lwIP (or perhaps uIP) I shall use to get a basic TFTP
> communication working? I guess I would need ARP, IP and UDP (but which
> files?). Would be great if somebody even could provide a functional
> example.

I would recommend to compile all files and use lwipopts.h to strip down code size (most of the files are then automatically left out through #if's).

Then, copy opt.h and define everything to 0 you don't need. I think there are some recommendations regarding size in the lwip wiki.
You should set NO_SYS to 1 (unless there's an OS in your bootloader), and you can at least turn off (LWIP_-) TCP, ICMP, IP_FRAG/_REASS, RAW, NETCONN and SOCKET. Regarding RAM usage (not code size), you will want to configure the MEM/MEMP settings as low as possible, although you need to tweak this after your application is finished.

Oh, and I guess you'd nee DHCP, too, for your client to get an IP address. The current code doesn't allow it, but I have a change in preparation that parses the bootloader file returned by the DHCP server.

And last but not least, I'd greatly appreciate if you could share the code with us: I'd like to add such a boot-client to the dhcp client code...


Simon

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