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

[Tom Rini]

On Thu, Jan 10, 2019 at 09:11:53AM +0100, Simon Goldschmidt wrote:
> On Thu, Jan 10, 2019 at 9:00 AM Stefano Babic <sbabic at denx.de> wrote:
> >
> > Hi Tom, Soeren,
> >
> > On 09/01/19 23:39, Tom Rini wrote:
> > > 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.
> >
> > I am not sure if we should point to EFI as responsible for the increased
> > footprint or it is due to the sum of several components / factors. I
> > just report my experience in last month : I had to port U-Boot for a
> > customer from a not very old release (2017.01) to the current. 2017.01
> > had already (apart of FIT support) all features the customer needed, but
> > there are issues(NAND, UBI) and I kew that they were solved later.
> > Processor was an old PowerPC 8308, a quite dead SOC. I have not changed
> > a lot in board code, but of course I had to reconfigure a lot. At the
> > end, everything worked but I was quite astonished about footprint. I had:
> >
> > 2017.01 u-boot.bin 443452
> > 2018.11 u-boot.bin 654684
> >
> >  But the new footprint overwrote the space for the env, and I had to
> > change the layout.It was not something that I could not manage and in
> > this specific case, customer could handle it. I cannot say I did
> > something pretty wrong to bloat the bootloader, so my feeling was that
> > there is not a specific part responsible for the increased size, but
> > each component is slightly bigger and they sizes sum at the end.
> >
> >
> > >  Why default?  Well, "everyone"
> > > agrees that defaulting to EFI application support means the widest
> > > choice of out of the box software support.
> >
> > I am unsure about this - just my two cents.
> >
> > I agree with you if we are talking about evaluation boards and / or
> > boards supposed to run different distros (or in any case, more flavour
> > of software).
> >
> > But there are a lot of "custom" boards (maintained in U-Boot) that runs
> > for a specific project and won't run any other kind of software. If a
> > device is a navigation system, a network controller, or whatever, it
> > will just do this job until its EOL.
> >
> > Specially for older boards, a new feature should not be activated as
> > default. At the beginning, police in U-Boot was to set just what should
> > be required in the bootloader, without setting what is not needed as
> > default. So default was off instead of on.
> 
> I aslo think that would suit U-Boot better. For example, I have one
> configuration where I need to squeeze U-Boot into 204 KiB. For me this
> currently means I have to re-check the defconfig for every update to
> disable new features that are now on by default. I think having those
> default to off and enabling them via defconfig if required would be better.

Can SoCFPGA not set the option to make a link failure if you grow beyond
204KiB?  As part of this thread, the only new default y thing since
v2018.01 at least is CRC16-CCITT support in "hash".

-- 
Tom
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