[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 05:36:11PM +0100, Simon Goldschmidt wrote:
> Am 10.01.2019 um 16:56 schrieb 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".
> 
> Well, this is a non-mainline config. Plus I keep having problems with the
> size check in that it does not account for the DTB. Wait, that was for SPL,
> how do you enable a size check for U-Boot?

We have CONFIG_BOARD_SIZE_LIMIT, which I would be unsurprised to learn
also needs to be used in just a few more targets in the top-level
Makefile.

> Anyway, if new default y things aren't the problem, it's probably an
> increasement here and there, like Stefano said... :-(

Well, which part?  There's the huge jump that I want to see what's going
on with on Stefano's PowerPC board.  Looking at SoCFPGA for that
time-frame, wow, there's a lot of growth due to how we've fixed things
in FAT write support.  Then it's EFI fixes and UBI fixes.  A lot of that
growth could be returned by dropping LOGLEVEL.  In fact, a quick test of
going down to CONFIG_LOGLEVEL=2 shows a net reduction of 6KiB instead of
40KiB growth.

-- 
Tom
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