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

Marek Vasut marex at denx.de
Fri Nov 22 01:38:51 UTC 2019

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.

>>>>> 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.

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