Issues with converting an RPX to an ELF and back

[BullyWiiPlaza]

wut-tools includes an elf2rpl utility but no rpl2elf utility.

Tools which perform the latter exist in the following:

• https://github.com/Relys/rpl2elf
• https://github.com/0CBH0/wiiurpxtool ("improved" rpl2elf)

Chaining together Hykem's rpl2elf and elf2rpl from wut-tools however does not work and yields the following error:

>rpl2elf Foo.rpx Foo.elf
>elf2rpl Foo.elf Foo.rpx
ERROR: Unsupported relocation type 252
ERROR: Unsupported relocation type 253
ERROR: fixRelocations failed.

Questions:

• Why does Hykem's rpl2elf produce an invalid ELF which cannot be ran on the Wii U? Is there an issue with writing out the relocations?
• wiiurpxtool can successfully compress and decompress RPX files by itself but decompressing with wiiurpxtool and then re-compressing with elf2rpl does not work with the same error(s) from above. Why does wiiurpxtool succeed at recompressing but elf2rpl does not? It seems like wiiurpxtool also produces a valid RPX once again which can be ran successfully. Which tool is more correct in its behavior?

To clear up the confusion an "official" wut-tools rpl2elf binary or some more insight into the conversion situation would be great.

[asiekierka]

What's the use case, from the perspective of homebrew development, of converting an RPX to an ELF?

[BullyWiiPlaza]

@asiekierka The use case is for example to convert a game RPX/RPL to an ELF for easier analysis or modification for game modding purposes. Also in terms of homebrew if you can't recompile an RPX/RPL you may still be able to adjust it via editing the ELF file either because the dependent libraries are gone/undefined or because you don't have the source code in general.