[yocto] Build optimization question

[Dean]

So I am using core-image-minimal and trying to shrink things as much as 
possible for boot speed. I wrap the bitbake command in some other 
commands to basically extract the image and then attach it to a kernel 
as a ramdisk. So the size of the image is critical to boot speed.

In some of my custom packages I have used -Os in the gcc command line.
Is there a way to set this globally for all the packages built into the 
image?

Any other hints or tips to reduce the size of the build? Or potential 
changes to u-boot to make it load faster? This is running on a 
beaglebone black.


Thanks,
Dean