Follow-up: Mixed DWARF32/DWARF64 section ordering in ELF

[刘可]

Hi,

I’d like to follow up on the 2020 discussion, “Reserve a section type value for DWARF64”:

https://groups.google.com/g/generic-abi/c/i2Xio-47QdQ/m/Qq8-76noAwAJ

The same problem has come up again in current LLVM/LLD work. When DWARF32 and DWARF64 input sections are mixed, a DWARF32 contribution may be placed at a high offset and cause relocation overflow.

We are looking for an ELF-level producer/linker contract that allows the linker to order these contributions without parsing DWARF contents. The appropriate representation and scope are still open questions; the mechanism may need to apply beyond .debug_*, for example to .eh_frame.

The current LLVM RFC is here:

https://discourse.llvm.org/t/rfc-use-sht-dwarf64-for-lld-dwarf32-dwarf64-debug-section-ordering/91190

Before proceeding with an implementation, I would appreciate guidance on:

• whether this problem warrants a generic ELF ABI extension;

• what representation and semantics would be appropriate;

• how such a mechanism should remain compatible with existing linkers and consumers.

Thanks.