I'm fairly certain there is a bug in the COFF code. My particular problem is with coff-x86-64 in the development version of binutils, but I've had similar troubles with 32-bit coff in the past. I have rather large COFF object files built by MASM that I translate to ELF using objcopy. The instruction that isn't converting properly is: "mov rax, OFFSET some_variable" Dumpbin and objdump seem to indicate the relocation record for "some_variable" is not being converted properly. I'd be happy to provide you with source code, object files, or even work to get the smallest possible reproducible source file. If you're not interested in the problem, I'll find some way to work around the trouble. The similar 32-bit object file problem I had forced me to replace "CALL some_routine" with: push OFFSET xxx push OFFSET somer_routine ret xxx: This may have been fixed. I don't know as I've used macros to work around the problem for several years.
objcopy doesn't work very well on relocatable objectfiles from COFF to ELF since there are no exact 1 to 1 mappings for COFF vs. ELF relocations. However, you should be able to link against COFF object files to create an executable or shared library in ELF.
Further investigation: If some_variable is an EXTRN variable then "mov rax, OFFSET some_variable" works just fine. The problem only occurs when some_variable is declared in the same file as the "mov rax, OFFSET some_variable". Thus, I have an easy workaround.
Closing as workaround available and it is a lot of work to fix properly. (We'd need to have a common internal BFD representation for relocations on the different formats.)