[U-Boot] [PATCH 2/2] board: tbs2910: Remove FIT support in defconfig to reduce u-boot size

[Tom Rini]

On Wed, Jan 09, 2019 at 05:01:37PM +0100, Stefano Babic wrote:
> Hi Soeren,
> 
> On 08/01/19 12:03, Soeren Moch wrote:
> > Hi Stefano,
> > 
> > On 08.01.19 11:24, Stefano Babic wrote:
> >> Hi Soeren,
> >>
> >> On 08/01/19 11:14, Soeren Moch wrote:
> >>> Stefano,
> >>>
> >>> can you apply this for v2019.01? This is really a important fix to avoid
> >>>  environment and u-boot binary overwriting each other.
> >>> It is also a small local fix which cannot hurt anybody else.
> >> I will apply and I send a new PR. This is not the first fix in this
> >> direction, u-boot becomes pretty large, it is becoming a common problem.
> >>
> > Thank you very much.
> > 
> > Yes, "in the good old days (tm)" there was much effort put into not
> > increasing the binary size for existing boards when adding new features.
> 
> Right, fully agree.
> 
> > Unfortunately this is not true anymore.
> 
> I get in the same trouble with more as one project. A previous rule of
> thumb was to reserve 512KB to the bootloader because it was pretty
> unthinkable that bootloader could be larger. Mhmmhh....this remember me
> someone else who said that 640Kb is enough for everything.
> 
> Anyway, as you noted, this is a big problem in field and it makes
> difficult an upgrade without returning back the device to factory, what
> nobody wants.

So, this is more on me, so I should probably explain a little, and point
at the biggest culprit too.  The biggest at times culprit and sometimes
controversial thing is that we default to the EFI subsystem being on by
default.  This is 50KiB on tbs2910.  Why default?  Well, "everyone"
agrees that defaulting to EFI application support means the widest
choice of out of the box software support.

And I do look at size changes, at least per push to master.  So most of
the time it comes in "drips and drabs".  Right now I'm going to grow
tbs2910 by 60 bytes[1].  Most of that is section re-alignment and 8 of it
is the regression fix to mmc_startup() or non-DM MMC drivers.  But
that's not super interesting, so lets look at v2018.09 to now.  That's
1800 bytes.  That's not too bad and looks like it's maybe half bug
fixes, half working on various frameworks (sure, DM/DT stuff but also
hash algos.  If we jump back to v2018.01, so more or less a year worth
of changes, that's 19KiB.  Without trying to break down _everything_
that's a good bit of EFI and a little bit everywhere else.

> > And all the shiny new driver model / OF features only bring
> > disadvantages for maintainers and users of existing boards.
> > 
> > I totally understand the desire to convert the driver code to "something
> > better", which is easier to maintain long-term. But apparently new code
> > is only tested on a single platform, while constantly breaking support
> > for others without notice. But 'm complaining to the wrong person...
> 
> Yes, I am not the right person ;-)
> 
> I picked up your patches, I will run build tests and if everything is
> fine I will sent PR for 2019.01.

In retrospect, I wish more people knew about enforcing a link time hard
limit on the binary and knew about it a lot longer ago.  Because when
those failures pop up, I don't apply the new PR and I start talking to
the relevant parties to see what we can do.

[1]: buildman --step 0 -SBCdevlk followed by --step 0 -SsBdevlk to see
how much and where, and yes, that's a few more flags than I _need_ for
that, and since it's in a script I never go and optimize it down.

-- 
Tom
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