By the way, I think the example has a mistake. It uses copy-to-ebx, but the following paragraph in subx.md refers to copy-to-eax. (Edit: learned a bit more) S

By the way, I think the example has a mistake. It uses copy-to-ebx, but the following paragraph in subx.md refers to copy-to-eax. (Edit: learned a bit more) Since you're doing a syscall, it seems it may actually be correct for the "return value" (really the argument to the syscall) to be in ebx, so in that case you'd just want to change the text to agree.