[PATCHv8 00/15] net/lwip: add lwip library for the network stack

[Maxim Uvarov]

On Wed, 13 Sept 2023 at 01:27, Simon Glass <sjg at google.com> wrote:

> Hi Maxim,
>
> On Tue, 12 Sept 2023 at 05:42, Maxim Uvarov <maxim.uvarov at linaro.org>
> wrote:
> >
> > On Fri, 8 Sept 2023 at 19:59, Tom Rini <trini at konsulko.com> wrote:
> >
> > > On Fri, Sep 08, 2023 at 07:53:05PM +0600, Maxim Uvarov wrote:
> > >
> > > > Before apply these patches it  is needed to create lwIP merge into
> > > U-Boot:
> > > > git subtree add --prefix net/lwip/lwip-external
> > > https://git.savannah.nongnu.org/git/lwip.git master --squash
> > > > or
> > > > create git submodule, depends how it's more easy to maintain external
> > > > library.
> > >
> > > So, I think we're going to go with subtree.  Please work out how to
> > > integrate the above in to the build process automatically (and such
> that
> > > we can maintain it via upgrades moving forward).
> > >
> > > --
> > > Tom
> > >
> >
> > I did not find a good way to friend git format-patch, git am and subtree.
> > And now with using subtree I can provide my thoughts, in general I do not
> > see any big advantages
> > with maintaining subtree code.
> >
> > Problem is that:
> >
> > 1. subtree does some root reset. So rebase looks like:
> > label onto
> >
> >
> >
> > # Branch acbc0469a49de7055141cc730aa9c728e61b6de2-2
> >
> > reset [new root]
> >
> > pick acbc0469a4 Squashed 'net/lwip/lwip-external/' content from commit
> > 84fde1ebbf
> > label acbc0469a49de7055141cc730aa9c728e61b6de2-2
> >
> >
> >
> > reset onto
> >
> > merge -C ec4a128c8d acbc0469a49de7055141cc730aa9c728e61b6de2-2 # Merge
> > commit 'acbc0469a49de7055141cc730aa9c728e61b6de2' as
> > 'net/lwip/lwip-external'
> > pick 739681a6f5 net/lwip: add doc/develop/net_lwip.rst
> >
> > pick f0ecab85e0 net/lwip: integrate lwIP library
> >
> > 2. if  --rebase-merges option was not provided to rebase, then rebase
> will
> > omit subtree directory and try to apply rebase patches to root directory.
> > I.e. in current case squashed commit for lwip, will be applied to uboot
> > root directory instead of ./net/lwip/lwip-external.
> >
> > 3. due to broken rebases without --rebase-merges more likely things like
> > git bisect also will not work.
> >
> > 4.  change in subtree code ./net/lwip/lwip-external/../something.c will
> > create a git commit which looks like a standard U-Boot commit. I.e. path
> > starts with ./net/lwip/lwip-external/
>
> I don't really understand most of the above, but I take it that
> subtree has some problems...I did find an article about subtree [1]
>
> >
> > 5. lwip maintains code with a mailing list.  So we don't need to push
> > subtree git somewhere to create a pull request.
> >
> > 6. I rechecked the latest edk2 and they use submodules now. (openssl,
> > libfdt, berkeley-softfloat-3 and others).
> >
> > 7. dynamic download also looks horrible for me. I.e. create subtree in
> > Makefile on compilation process. I think maintaining that will give you a
> > bunch of problems. I think we should not touch git structure after
> cloning.
> >
> > So what I can here suggest:
> > 1.  lwip source code is 9.4M.  If we compare all code it will be 564M in
> > total. So just having 1 commit witn copy of lwip library will work here.
>
> So we add a 9.4MB patch for the code we need? I suppose that is OK,
> although it is much larger than net/ today (0.5MB).
>
> What is the churn on lwip? E.g. would it be easy to add a commit every
> few months to bring in upstream changes?
>
> >
> > or
> >
> > 2. use git submodules. Size of the project will be lower.  Submodule will
> > not allow you to use local changes. I.e. change needs to be merged into
> the
> > upstream project and then you can update git HEAD for the submodule.
>
> I really don't want to work with a submodule project. I've just had
> too many problems.
>
> >
> > or
> >
> > 3. inside u-boot.git create branch lib-lwip and clone lwip repo there.
> Then
> > use git submoule to connect this branch as a folder to the main U-Boot
> code.
>
> It really needs to be properly part of U-Boot.
>
>
Ok. Then more likely we don't need all the git history of lwip inside
uboot.git. Then the option with a single commit is more preferable.
Then we can use part 2 of this article, how to  go with standard git
commands:

1.
<cmd>
git remote add -f lwip https://git.savannah.nongnu.org/git/lwip.git
git read-tree --prefix=net/lwip/lwip-external -u lwip/master
git commit -m "lwip merge sha: xxxx"
</cmd>
this will create a git format-patch friendly commit. Then we send it to the
mailing list  and apply.
I hope the mailing list will allow us to send a 7.8 MB patch.


Then if for development you need  to pull he history of lwip, you can do it
with:
git pull -s subtree lwip  master --allow-unrelated-histories
(but I think nobody will need this.)

New update of the lwip net/lwip/lwip-external dir will be done with:
git pull -s subtree lwip  master --allow-unrelated-histories --squash
Squash commit also has to be git format-patch friendly.

If you are ok with that proposal I will send v9 with the first patch
created with steps above.

Thanks,
Maxim.







> >
> > BR,
> > Maxim.
>
> Regards,
> Simon
>
> [1] https://www.atlassian.com/git/tutorials/git-subtree
>