[U-Boot] __FILE__ usage and and SPL limits for SRAM

[Nishanth Menon]

Hi,

we've kind of run into an interesting situation recently, but might be 
of interest for various folks trying to reduce the image sizes.

our AM335x device has a limited amount of sram.. and the SPL tries to 
fit into it (a bit tricky given the restricted space we have on it on 
certain class of devices).

arch/arm/mach-omap2/am33xx/u-boot-spl.lds is a bit custom tailored 
around this.

Key in this is:
. = ALIGN(4);
.rodata : { *(SORT_BY_ALIGNMENT(.rodata*)) } >.sram

. = ALIGN(4);
.data : { *(SORT_BY_ALIGNMENT(.data*)) } >.sram


Now, our jenkins build system happens to use a varied build path and 
uses O= path. to simplify the details:
mkdir 
/tmp/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb/cccccccccccccccccccccccccccccccccccccccccccccccccc
mkdir 
/tmp/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb/cccccccccccccccccccccccccccccccccccccccccccccccccc/b

git clone u-boot
cd u-boot

git clean -fdx
make CROSS_COMPILE=arm-linux-gnueabihf- O=../b am335x_evm_defconfig
make CROSS_COMPILE=arm-linux-gnueabihf- O=../b all

depending on depth of the path, this would fail.. a little bit of 
headscratching later..
when using O= build system uses absolute paths, which translates to 
__FILE__ being absolute paths as well..

in u-boot, any printf("%s", __FILE__) makes u-boot allocate this file 
path in rodata.

So, depending on how deep the path is rodata size varies and ends up 
pushing .data out of sram max range.

we dont really care to put a print of complete absolute path anyways, 
and I am not really sure of a clean way to resolve this:
a) override __FILE__ with something.. -Wbuiltin-macro-redefined kicks in
b) replace usage of __FILE__ with something like __FILENAME__ as 
recommended by [1]


What is the suggestion we do?

[1] http://stackoverflow.com/questions/8487986/file-macro-shows-full-path
-- 
Regards,
Nishanth Menon