[RFC PATCH 0/5] LWIP stack integration

[Tom Rini]

On Fri, May 19, 2023 at 04:17:06PM +0300, Ilias Apalodimas wrote:
> Hi Tom, 
> 
> Apologies for being late to the party
> 
> > On Thu, May 11, 2023 at 09:52:04AM -0400, Tom Rini wrote:
> > On Fri, May 05, 2023 at 10:25:24AM +0000, Maxim Uvarov wrote:
> > 
> > > Greetings,
> > > 
> > > This RFC patchset is an attempt to try to use an already existing IP network stack inside U-boot.
> > > U-Boot recently got basic TCP/IP support, implementing wget, but in order to get a full IP stack
> > > with new features (e.g ipv6), it would be preferable to use an established embedded ip library,
> > > instead of rewriting the code from scratch.
> > > 
> > > For this experiment LWIP network stack was selected:
> > > https://savannah.nongnu.org/git/?group=lwip
> > > 
> > > LWIP main features include:
> > > - Protocols: IP, IPv6, ICMP, ND, MLD, UDP, TCP, IGMP, ARP, PPPoS, PPPoE
> > > - DHCP client, DNS client (incl. mDNS hostname resolver), AutoIP/APIPA (Zeroconf),
> > >   SNMP agent (v1, v2c, v3, private MIB support & MIB compiler)
> > > - APIs: specialized APIs for enhanced performance, optional Berkeley-alike socket API
> > > - Extended features: IP forwarding over multiple network interfaces, TCP congestion control,
> > >   RTT estimation and fast recovery/fast retransmit
> > > - Addon applications: HTTP(S) server, SNTP client, SMTP(S) client, ping, NetBIOS nameserver,
> > >   mDNS responder, MQTT client, TFTP server.
> > > 
> > > This RFC work is a demo to enable lwIP (lightweight IP) which is a widely used open-source 
> > > TCP/IP stack designed for embedded systems for U-boot. That will allow using already 
> > > written network applications for microcontrollers.
> > > 
> > > lwIP is licensed under a BSD-style license: http://lwip.wikia.com/wiki/License.
> > > Which should be compatible with u-boot.
> > > 
> > > In the current RFC I tried to use minimal changes to better see how LWIP code can be embedded into
> > > U-boot. Patches implement ping and wget commands work. Both commands are currently copy pasting and
> > > reusing lwIP examples.  Whether we want to add the final application in U-Boot or lwIP is up to 
> > > discussion, but the current approach was the easiest one for an RFC.
> > 
> > I'm honestly not sure this is the most useful way of doing an RFC.  The
> > long term goal would be that we replace our existing net/ with lwIP,
> > yes? So what I'd see as more valuable is what it looks like to limit
> > yourself to either sandbox or some QEMU target, disable the current
> > network stack, and instead use lwIP to support just cmd/net.c so that
> > the scope of the conversion is visible.  Then the size comparison you do
> > should be between platform + net + cmd/net.c (and the rest of networking
> > turned off) and platform + lwip + cmd/net.c converted.
> 
> This might be a bit too much imho.  How about replacing the TCP stack which
> is new an under heavy devel as well.  If we do that we could replace lwip
> with the version Maxim proposes and check the difference between
> U-boot + homegrown TCP + wget
> U-Boot + LWIP (for tcp only) + new wget
> 
> That would give us an idea before trying to replace the UDP portion which
> is way bigger

I guess we can try that as a starting point and see what things look
like.  My gut feeling however is that's not going to look like a win.

-- 
Tom
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