[PATHv11 26/43] configs/tbs2910_defconfig inc limit

[Tom Rini]

On Tue, Dec 05, 2023 at 07:25:15PM +0100, Soeren Moch wrote:
> 
> 
> On 05.12.23 17:25, Maxim Uvarov wrote:
[snip]
> > The problem is that for many targets the limit is 1MB.
> For tbs2910 it is 383kBytes. And there was plenty of free space when I
> introduced mainline u-boot support. But yes, space got tighter over time.

And I do not want to say "minimum flash size for U-Boot is 1MB", either.
Nor 512kB. We're never going to be as tiny as we used to be, but I will
be unhappy if we can't keep something like tbs2910 and a limit of
almost-384kB functional and useful.

> > U-Boot in some minimal configuration is about 500kb. But U-boot with
> > EFI, USB, Eth drivers,  MMC, RTC, and all the commands is 900+ kb and
> > very close to 1MB. Most of the new features are enabled by default.
> No. Tom does a very good job to ensure that there is no (not much)
> additional space required for unrelated boards that do not need new
> features.
> > I.e. they do not exist in _defconfig and appear in the resulting
> > .config automatically.  I would say that for some small targets things
> > like EFI, Secure boot, TPM, Updates and many others are not needed.
> > But if new features will appear by default very soon we will see limits.
> New features will not be enabled for old space constrained boards. In
> your series you did not offer to keep the old implementation instead,
> this is different and the reason why we discuss image size constraints.

So here is where things get tricky. I _really_ don't want to have two
network stacks. And one of the remarks I believe you had made years ago
Soeren was along the lines of "why does my platform need this new
stuff?" to which I think this time, I have a good answer. Our homegrown
networking stack is fragile and difficult to maintain. lwIP is well
maintained and also open to feedback / improvements from U-Boot to make
it more configurable (so, trimmed down further in size). So I really do
want to replace our stack with something with better long term
maintenance and less bugs, while not growing things too much either.

And to that end, we aren't there just yet with lwIP merging in either.
We're getting better than earlier iterations. And we will have
old-or-new as at least a build time option for a few releases so it
might be the case that we allow the new stack to come in with a note
that it won't become the default stack until the final sets of size
issues / functional configurability is done.

-- 
Tom
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