Re: [U-Boot] [PATCH 1/1] x86: detect unsupported relocation types

On 10/24/2018 08:58 PM, Hannes Schmelzer wrote:

...

Hello Hannes,

thanks for reporting the problem.

There are two possible reasons:

a) The build process introduces relocations of the reported type. b) The relocation records are overwritten before relocation. This happens if you update uninitialized globals.

To analyze your problem further, please, provide instructions for building your version of U-Boot (repository, commit, config). That will allow to check for a).

Coreboot can be run on QEMU (https://www.coreboot.org/QEMU). QEMU would allow to analyze case b). Are you able to reproduce the problem with QEMU?

Best regards

Heinrich

Hello Heinrich,

thanks for this input. The "trouble" occurs also with QEMU, have a look to console output below.

Maybe you can investigate on this, I've pushed the branch to my github account:

https://github.com/oe5hpm/u-boot/tree/bur-next-pp065mb config is "brpp065mb"

please let me know if i can help.

cheers, Hannes

And running qemu-x86_defonfig results in do_elf_reloc_fixups32: unsupported relocation type 0x2 at fff84e38, offset = 0xfff00091

So the problem is not restricted to your board.

I have had a first look at the relocations actually present in the u-boot ELF file.

Your repo: make brpp065mb_defconfig make objdump -r u-boot | cut -c10-20 | sort | uniq

R_386_32 R_386_NONE R_386_PC32

u-boot master: make qemu-x86_defconfig make objdump -r u-boot | cut -c10-20 | sort | uniq

R_386_16 R_386_32 R_386_NONE R_386_PC16 R_386_PC32

The current relocation code only supports a single relocation type (R_386_RELATIVE).

What I still do not understand is why most of the relocations that we actually see inside U-Boot are of type R_386_RELATIVE). So where are the relocations transformed on the way from u-boot to u-boot.bin?

The following command drops some sections and creates an image without any relocation information:

objcopy --gap-fill=0xff -O binary -R .start16 -R .resetvec u-boot u-boot-nodtb.bin

But where are the R_386_RELATIVEs created?

@Bin: do you have an understanding of how this works?

Best regards

Heinrich