On Mon, 27 Jun 2011 11:36:33 +0200 Wolfgang Denk wd@denx.de wrote:
Dear Aneesh,
In message 4E080733.2030001@ti.com you wrote:
I wonder why do we need this whole spl thing in the first place (well, surely I know what they are used for but why do we need a separate entity for this)? Isn't it just the same U-Boot in, well, very special configuration (minimal set of drivers, no shell, etc)? Why do we need a whole shadow tree at spl/ instead of just providing the _configuration_?
Am I missing something?
The reason is that the regular U-Boot is not configurable enough to build the extremely small images that should fit in internal RAM. The last time I attempted, I ended up getting an ~60KB image for OMAP4(that too without any of the hardware initialization I am adding in my SPL work).
This statement does not make much sense to me. If we can do it in the spl/ directory, we should be able to do it in any other directory as well. The worst to happen is that we have to keep two setsof object files separated, but chosing a different suffix should be sufficient.
We do it in the spl/ directory by bypassing the normal makefile config system, specifying a board-and-spl-specific list of objects instead.
It could of course be done with the standard config system, but it will require that every bit of code in U-Boot be enabled only with a particular config option -- no "always on" code. This would be a good thing anyway, but it will take some work to do it cleanly. A first step would probably be a global "finegrained/small" flag that configs use to opt into the new system, but eventually all bits of functionality should have appropriate individual config symbols.
-Scott