On Fri, Dec 16, 2011 at 10:20 AM, jonsmirl@gmail.com jonsmirl@gmail.com wrote:
The CPU I'm working with, the LPC3130, is kind of an in-between CPU for SPL. Instead of a tightly constrained RAM of 16KB or so I have 96KB to work with. 96KB is enough room to support all of the various boot modes (uart, nand, spi, USB, etc) but not enough room for the full uboot command set. So I'm still stuck with the SPL model, but my constraints are much less.
One example of a conflict with SPL is NAND support. With SPL you hard code in the NAND type. In my case I have enough room to do NAND type detection. So this has me modifying the #ifdefs in the makefiles to include the NAND detection code in my SPL loader.
I'm wondering if SPL could be designed in a more generic manner. Another model would be to use SPL as the base layer for all u-boot builds. You would then start turning on features until full uboot capability was reached. An example of this would be NAND support, the default would be hard coded NAND for all u-boot builds, but turning on NAND detection would increase the size of the build and disable the hard coded support. Another default would be SPL chaining into the next image, turning on the u-boot UI would again make the code larger and disable auto-chaining.
So, in chasing down another problem I was having (that turned out unrelated) I just made SPL use the full NAND stack. It wouldn't be difficult to add CONFIG_SPL_FULL_NAND_SUPPORT (and either keep the existing name for nand_spl_simple or rename to CONFIG_SPL_MIN_NAND_SUPPORT). I've even got the tree I did that hack in around on github if you want a reference.