re: ELF psABI definition for VAX?

["Maciej W. Rozycki" <macro%orcam.me.uk@localhost>]

On Sun, 2 Feb 2025, matthew green wrote:

> > am> And actually it is not much to document.  The relocations maybe?
> > am> The ELF implementation was written by Matt Thomas many years ago.
> >
> > am> What are you more specifically thinking about?
> >
> > I am writing tests for Elftoolchain's handling of VAX-related symbols, and
> > am looking for ABI-related reference documentation.
> 
> unfortunately, i don't recall ever seeing a document for it,
> but reading src/libexec/ld.elf_so/arch/vax/ and vax/elf_machdep.h
> gives what appears to be almost all the details:
> 
>  - caller/callee same as a.out
> 
>  - 11 reloc types defined, but only 6 appear to be used (including
>    "NONE")

 Hmm, I can see 4 static: R_VAX_32, R_VAX_GOT32, R_VAX_PC32, R_VAX_PLT32, 
and 4 dynamic: R_VAX_32, R_VAX_GLOB_DAT, R_VAX_JMP_SLOT, R_VAX_RELATIVE 
relocations used, totalling 7.

 Don't forget PLT stuff (done in an odd way; MIPS-style SVR4 lazy binding 
stubs would be more suited rather than x86-style PLT, given the VAX ISA 
providing indirect addressing, so as to simplify handling and avoid the 
mess PLT causes with symbol equality for protected function symbols), PIC 
data symbol reference indirection affecting the choice of address modes 
permitted, etc.

  Maciej