Hi Jerry:
2009/2/24 Jerry Van Baren gerald.vanbaren@ge.com:
loody wrote:
Dear all: While porting uboot, I find there are too many things I don't need at all, like net, i2c etc. How could I remove them from my uboot binary to minimize the size of uboot, my flash limitation is 6k?
If 6K is truly what you have, you aren't going to get there with u-boot. I don't know what the current minimum config results in (and it will vary depending on processor and the definition of "minimum"), but rule of thumb is that 128K is a fairly tight u-boot; under 128K and you will be cutting deeply. It may be possible to get it under 64K with a lot of work, but it may be easier to start with a different code base or start from scratch.
Can you do a two level bootstrap where you have a 6K minimal bootstrap program that loads u-boot from somewhere else that has 128K-256K available? Note that this is what NAND-booting systems (e.g. ARM) do - the NAND first stage boot fits in 4K, the rest gets copied from NAND to RAM and then run in RAM.
Thanks for your kind suggestion. If I only need uboot to do cpu basic setting with USB ehci and file system support, does it still need 128k at least? As you suggest, I can do the 2 levels bootstrap. But uboot has great features support. I am not sure it will be easier to make another wheel.
Sorry, unless there is a really significant typo in your original email, u-boot has way too much functionality for your constraints. I don't know what the alternatives are (there are some), but you are looking at a very tight boot ROM probably written mostly/entirely in assembly or very constrained C (no libraries, very tightly written, max optimization).
Would you please tell me how to add a new cpu and platform in uBoot? I know the first step I have to do is adding my cpu and platform folder. But I have no idea how to add setting in Makefile. why sometimes we use "@$(MKCONFIG) $(@:_config=)" ,sometimes we use "@$(MKCONFIG) -a" and sometimes we have to " @mkdir -p $(obj)include" before calling mkconfig?
I try to modify platform.h located at include/configs to remove unnecessary driver. But I have no idea which one I can remove such that the unnecessary driver will no compile my uboot. for example, I remove "CONFIG_DRIVER_CS8900" in smdk2410.h, and the error message while linking is "net/libnet.a(net.o): In function `NetSendPacket': /media/u-boot_20090224_snapshot/net/net.c:654: undefined reference to `eth_send'" Appreciate your kind help, miloody
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I want to add my cpu and platform and find out where the bottle net is.