[U-Boot-Users] booting elf images from flash
Robin Getz
rgetz at blackfin.uclinux.org
Sun Mar 20 15:57:39 CET 2005
I know that U-boot currently supports booting compressed binary images from
flash via the instructions in the README
Building a Linux Image:
-----------------------
* build a standard "vmlinux" kernel image (in ELF binary format):
- this works
* convert the kernel into a raw binary image:
${CROSS_COMPILE}-objcopy -O binary \
-R .note -R .comment \
-S vmlinux linux.bin
In our system architecture (Blackfin) SDRAM (133MHz) is at 0x0 to0x07FFFFFF
(128Meg), and on chip Instruction SRAM (runs at core speed - up to 600MHz)
exists at 0xFFA00000 to 0xFFA13FFFF (64k). Some of our kernel drivers need
to put code snippets in SDRAM at 0xFFA00000.
Today - we did this by modifying the lds, and letting the linker manage
everything. However, this breaks ${CROSS_COMPILE}-objcopy as it tries to
dump ~4.0Gig into the bin file...
I can see a few options:
- revert back to have drivers copy their information into SRAM (which
makes kernel maintenance a problem - as all kernel modules writers need to
know where everyone else is doing things, so they won't copy over each other)
- give more options to objcopy, and make 2 bins (one for SDRAM (kernel),
one for SRAM (drivers)), load these separately, and execute from kernel. I
am assuming that this wouldn't be much different than loading a ramdisk
separately from kernel images.
- write a patch to accept compressed elf files in U-boot, rather than
just compressed bins.
Thoughts/Opinions?
Thanks
-Robin
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