Hi all,
I've got an interesting issue with a MIPS board I'm working on. The uncompressed uImage has been created with a Load Address of 0x80500000 and an Entry Point of 0x80504590. This gets TFTP's into RAM at 0x8055b728. When I run a "bootm 0x8055b728" this image fails to run. Tracing through the code, I see that in bootm_load_os() it follows the IH_COMP_NONE path for non XIP images. This should copy the uImage to the load address so it can be executed.
However, the copy command is : memmove_wd ((void *)load, (void *)image_start, image_len, CHUNKSZ);
This actually copies the image 'payload' instead of the whole uImage thereby dropping 64 bytes from the front of the copy and moving the entry point. (I've verified this by breaking into the process and looking at the source and destinations of the copy and comparing to an XIP bootm invocation) I've scratched my head as I'm really surprised that it behaves this way with a zillion boards out there, BUT from digging via google it seems that the world and his/her dog nearly always use the same address for both load address and entry point which subsequently masks this behaviour in that particular case. I've verified that if I change to : memmove_wd ((void *)load, (void *)blob_start, image_len + (blob_end - blob_start), CHUNKSZ); Then the kernel boot works as I'd expect it to.
Can anyone sanity-check my reasoning here and tell me if this is the correct fix or if I'm being mislead by something more insidious that just happens to present itself in this way....?
Cheers!
~Pev