[U-Boot] Maximum size of u-boot.imx for TBS2910 board

[Marek Vasut]

On 11/22/19 3:53 AM, Tom Rini wrote:
> On Fri, Nov 22, 2019 at 02:38:51AM +0100, Marek Vasut wrote:
>> On 11/22/19 2:30 AM, Tom Rini wrote:
>>> On Fri, Nov 22, 2019 at 02:27:16AM +0100, Marek Vasut wrote:
>>>> On 11/22/19 1:32 AM, Tom Rini wrote:
>>>>> On Fri, Nov 22, 2019 at 01:23:56AM +0100, Marek Vasut wrote:
>>>>>> On 11/21/19 11:45 PM, Tom Rini wrote:
>>>>>>> On Thu, Nov 21, 2019 at 11:01:43PM +0100, Marek Vasut wrote:
>>>>>>>> On 11/21/19 10:59 PM, Heinrich Schuchardt wrote:
>>>>>>>>> On 11/21/19 9:12 PM, Tom Rini wrote:
>>>>>>>>>> On Thu, Nov 21, 2019 at 09:09:29PM +0100, Heinrich Schuchardt wrote:
>>>>>>>>>>> Hello Soeren,
>>>>>>>>>>>
>>>>>>>>>>> when trying to add support for function key support in the USB keyboard
>>>>>>>>>>> driver u-boot.imx for the TBS2910 surpassed the maximum size for
>>>>>>>>>>> u-boot.imx.
>>>>>>>>>>> https://travis-ci.org/marex/u-boot-usb/builds/614059004
>>>>>>>>>>>
>>>>>>>>>>> Do you remember why on the TBS2910 board this size is limited to
>>>>>>>>>>> 0x5fc00? Other i.MX6 boards like the Wandboard allow a much larger
>>>>>>>>>>> u-boot.imx.
>>>>>>>>>>>
>>>>>>>>>>> The limit is defined here:
>>>>>>>>>>> include/configs/tbs2910.h:80:
>>>>>>>>>>> #define CONFIG_BOARD_SIZE_LIMIT 392192 /* (CONFIG_ENV_OFFSET - 1024) */
>>>>>>>>>>>
>>>>>>>>>>> Could the value CONFIG_ENV_OFFSET=0x60000 be enlarged?
>>>>>>>>>>>
>>>>>>>>>>> Many i.MX6 defconfigs use CONFIG_ENV_OFFSET=0xC0000.
>>>>>>>>>>
>>>>>>>>>> The nature of these boards (aimed at end users) means that we just do
>>>>>>>>>> not want to / cannot really move the stored environment.  Thanks!
>>>>>>>>>
>>>>>>>>> Another possibility would be to reduce the image size by using
>>>>>>>>> CONFIG_REGEX=n which should be fine for a board with only one supported
>>>>>>>>> network interface.
>>>>>>>>
>>>>>>>> But the board was fine before your patchset got applied and this is just
>>>>>>>> a workaround for added bloat, which reduces functionality. I dislike
>>>>>>>> trading functionality for bloat, sorry.
>>>>>>>
>>>>>>> One persons "bloat" is another persons "added functionality".
>>>>>>
>>>>>> It would seem this board did not suffer from the lack of this particular
>>>>>> functionality before, and I would say that a board should stay at least
>>>>>> as functional as it was when it was added. Replacing existing
>>>>>> functionality with random unrelated new one makes no sense.
>>>>>
>>>>> Was it tho?  I believe we're talking about supporting some additional
>>>>> keys via USB keyboard.  This board does in fact expect users to be at
>>>>> the U-Boot prompt via USB keyboard.
>>>>
>>>> How did you reach this conclusion ? It seems to be some sort of devkit.
>>>
>>> It came up in one of the previous threads about this board and what we
>>> can / cannot do about the size constraint and the board maintainers
>>> unhappiness about the overall size growth and broken releases (until
>>> size growth became a link error on the platform).
>>
>> Link please ? It sounds relevant to this thread too.
> 
> https://lists.denx.de/pipermail/u-boot/2019-April/365297.html
> 
>>>>>>> I believe
>>>>>>> the specific changes in question that once again push this board over
>>>>>>> fall in to that grey area.  Whatever size-trimming the board maintainer
>>>>>>> is fine with next is fine with me, but needs to get ack'd by someone.
>>>>>>
>>>>>> Or, the other option is, make these new extra features configurable and
>>>>>> disable them on this board. And so there should be no size problem.
>>>>>
>>>>> But that direction leads to saying every slight bit of functionality
>>>>> requires a new Kconfig entry.  Some levels of bugfixes as well.
>>>>
>>>> The other option is, we will sink in bloat and suffer endless size problems.
>>>
>>> Yes, it is a hard balancing act.  Stepping back, perhaps a "minimal" or
>>> "complete" choice for USB HID devices would make sense and allow us
>>> further areas to reduce size, on the minimal portion.
>>
>> Or maybe there is a way to help compiler optimize that USB key code
>> handling better.
> 
> Perhaps.  But my point is that every little functional change or
> enhancement does not need a Kconfig option.

Except this leads to slow and steady accumulation of bloat, and as we
already see for quite a while, this is problematic for more and more boards.