GSoC project: #3850 Modular Network Stacks
Rajiv Vaidyanathan
rajiv.vaidyanathan4 at gmail.com
Mon Mar 22 15:11:22 UTC 2021
Dear mentors,
Thankyou for providing information about the project. I want to pursue this
as my GSoC project. From the above discussion, I understand that the
following has to be done:
1. Collecting existing lwip drivers for BSPs and writing new ones.
2. Adding config files for driver management and also add lwip to the
choice of networking stacks for RTEMS.
3. Write tests, examples and documentation
Please let me know if I am missing anything.
I have the following queries:
1. Should I buy a Beaglebone or can I do everything with QEMU? I have a
Raspberry Pi 3B+. Can I use it for hardware testing instead?
2. I have cloned the rtems-lwip repository. Is there any open issue and
documentation I can look into to get more understanding about this repos
and the project in general?
Thanks and regards,
Rajiv
On Mon, 22 Mar 2021 at 01:06, Christian Mauderer <oss at c-mauderer.de> wrote:
>
>
> On 21/03/2021 18:53, Joel Sherrill wrote:
> >
> >
> > On Sun, Mar 21, 2021, 12:47 PM Vijay Kumar Banerjee <vijay at rtems.org
> > <mailto:vijay at rtems.org>> wrote:
> >
> > Hi Rajiv and Joel,
> >
> > On Sun, Mar 21, 2021 at 9:06 AM Joel Sherrill <joel at rtems.org
> > <mailto:joel at rtems.org>> wrote:
> > >
> > >
> > >
> > > On Sun, Mar 21, 2021, 9:20 AM Rajiv Vaidyanathan
> > <rajiv.vaidyanathan4 at gmail.com
> > <mailto:rajiv.vaidyanathan4 at gmail.com>> wrote:
> > >>
> > >> Hello RTEMS community,
> > >>
> > >> I found the ticket: Modular Network Stacks interesting. It would
> > be great if someone can tell the current status of this ticket and
> > what contributions can be done as a GSoC project.
> > >>
> > >> In the prerequisites list given, I have experience in UNIX
> > socket programming (in C and python), OSI model, basic Wireshark but
> > I don't have much experience in assembly (I can read assembly but
> > haven't written assembly code) and device drivers. It would be great
> > if someone can guide me if I can take up this project.
> > >
> > >
> > > Vijay is the primary mentor for this but I can give you an
> > outline of what there is to do.
> > >
> > > RTEMS historically had a 20 to 25 year old port of the FreeBSD
> > tcpip stack. This was ipv4 only and the source was included in the
> > main RTEMS repository. It was enabled or disabled via a configure
> flag.
> > >
> > > There is now the libbsd repository which is a port of the current
> > FreeBSD with many features and drivers. It has a focus on what we
> > call source transparency which means that we do not make changes to
> > it unless I absolutely necessary and try to preserve the original
> > source as much as possible. This makes it possible to largely update
> > the source using scripts. We currently track the FreeBSD 12 release
> > branch and their development version.
> > >
> > > With two tcp/ip stacks, it becomes necessary to be able to switch
> > between them. This project had a first step which was to move the
> > legacy stack into its own repository. Thanks to Vijay, you can now
> > build RTEMS without a tcpip stack at all. Then you download and add
> > on the tcp/ip stack of your choice - legacy or libbsd.
> > >
> > > But there's a third tcp/ip stack we are interested in. The lwip
> > stack is targeted at lower memory profiles and is not as full
> > featured as libbsd. We need an lwip RTEMS repository which includes
> > lwip, drivers for a variety of BSPs, its own build system, tests,
> > examples, and any services specific to lwip. Lwip as a project does
> > not do a good job of providing a central location for device drivers
> > so the RTEMS lwip repo will be a collection point. providing a
> > robust set of drivers and keeping track of where they came from and
> > maintaining Source transparency is key.
> > >
> > > This arrangement allows anyone to pick from the set of stacks we
> > support as long as they deal with the device driver.
> > >
> > > The GSoC project you would be proposing is the lwip part. We have
> > a build of it from a user's application to go by for a working
> > example of the stack. Probably completely ignore the default lwip
> > build system and uae a waf build system (Python).
> > >
> > The prototype for this repository is ready!
> > rtems-lwip: https://git.rtems.org/vijay/rtems-lwip.git/
> > <https://git.rtems.org/vijay/rtems-lwip.git/>
> >
> > This build follows a similar approach to rtems-libbsd and I have
> > also added a testcase to it, by modifying the networking01.exe from
> > the legacy repo.
> >
> > > I think this is very doable as GSoC project. Vijay already did
> > separate the legacy stack into its own repository, we have a test
> > case BSP, and there is a defined patter to follow.
> > >
> > I think the first step would be identify a target that we can run on
> > qemu as well as hardware and focus on that target. Porting that
> > target to LWIP would involve adding a driver to rtems-lwip, along
> > with a set up to manage the drivers. For managing different drivers,
> > I propose an ini or yaml configuration file that can be used by waf
> > scripts to decide which driver to build for a particular bsp.
> >
> >
> > I think Gedare and I chatted about this so I had some in mind. Zynq and
> > MPSoC have lwip drivers from xilinx and both run on qemu.
> >
> >
> https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18842366/Standalone+LWIP+library
> > <
> https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18842366/Standalone+LWIP+library
> >
>
> If it works with the zynq qemu BSP, I think that would be great for that
> kind of stuff. That BSP is always great for debugging (although most
> likely there will be few C-Code-Work in this repo) because you don't
> need extra hardware.
>
> >
> > The other top alternative is the PC.
>
> PC is hard for debugging. I never searched but I think you most likely
> don't find many with JTAG connectors ;-)
>
> Beagle could be an alternative for real hardware. I found at least one
> lwip driver for that.
>
> >
> > I can't remember what Alan Cudmore was using but it would be good to at
> > least include it so he can possibly provide feedback on his target.
> >
> > I would expect STM boards also have l whip drivers from the vendor in
> > their device driver kit.
>
> If there is a driver for one of the supported boards, that would be a
> nice target too. Most of the STM boards have debuggers already on board.
>
> Best regards
>
> Christian
>
> >
> >
> > So, roughly the todos for the application phase would be to identify
> > a potential target and divide the driver work in two phases as per
> > GSoC schedule. This also involves collecting all the old/previously
> > ported drivers in one place inside lwip, this will also act as a
> > reference on how to proceed with the driver for a new target.
> >
> >
> > Lwip is particularly bad at providing a unified place for drivers. This
> > is something I never wanted to happen with RTEMS. I think a big value of
> > this effort will be collecting drivers that can work with RTEMS bsps.
> >
> >
> >
> >
> > Best regards,
> > Vijay
> >
> > > That's the project in a nutshell. Vijay should speak up and add
> on.
> > >
> > >>
> > >> Thanks and regards,
> > >> Rajiv
> > >> _______________________________________________
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> > >
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> >
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