[U-Boot] Size of external u-boot commands

[Jon Smirl]

On Thu, Mar 26, 2009 at 9:52 AM, Jerry Van Baren <gerald.vanbaren at ge.com> wrote:
> Jon Smirl wrote:
>>
>> My networking hardware needs microcode loaded into it before it will
>> function. What's the best method to load this code? It's 70KB.
>>
>> My current u-boot image is 170KB. I started working with the code in
>> examples and api_examples. But the "hello world" programs built using
>> those APIs are 65-72KB in size.  That's almost half the size of my
>> u-boot image and these programs just print "hello world". Why are
>> these programs so big? My goal was to put the loader program and my
>> microcode into a single 128KB erase block.
>>
>> My code for loading the microcode into the hardware is 7KB. Now it
>> looks like I will need to incorporate it into the main u-boot image
>> instead of making it an external command.
>
> Hi Jon,
>
> I suspect the example code is 98% C libraries and 2% nugget.  In your
> example, "hello world" probably uses the whole printf support tree (strings,
> formatted printing, possibly floating point...).
>
> I would suggest you make a stand-alone application that simply returns and
> see how big it ends up.  Depending on whether that is small or not, check
> what libraries get linked with it and see how to create your simple test app
> such that it doesn't use any extraneous libraries.

Libraries appear to be the problem. A program that just returns is 100
bytes, add a puts("hello world") and it is 65KB.

I had expected the u-boot app examples to be smart and use the copy of
those libraries in the u-boot image. For example the demo program in
api_examples uses printf (65K library) instead of building an api
calling into u-boot for printf.



>
> HTH,
> gvb
>



-- 
Jon Smirl
jonsmirl at gmail.com