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Re: [PATCH] Fix distinction of 32/64bit addresses in MIPS gas
- To: "H . J . Lu" <hjl at lucon dot org>
- Subject: Re: [PATCH] Fix distinction of 32/64bit addresses in MIPS gas
- From: cgd at broadcom dot com
- Date: 06 Sep 2001 10:59:29 -0700
- cc: ica2_ts at csv dot ica dot uni-stuttgart dot de,binutils at sources dot redhat dot com
- References: <20010831181657.A17249@rembrandt.csv.ica.uni-stuttgart.de><200108311711.KAA19709@geoffk.org><20010831193107.A10362@rembrandt.csv.ica.uni-stuttgart.de><firstname.lastname@example.org><email@example.com><20010831204556.C17249@rembrandt.csv.ica.uni-stuttgart.de><firstname.lastname@example.org><email@example.com> <20010831143107.A4532@lucon.org><firstname.lastname@example.org><20010906105014.A32456@lucon.org>
"H . J . Lu" <email@example.com> writes:
> > > What is the 32bit address of `foo'?
> > bit 31 may or may not be set, depending on what exactly you're
> > compiling.
> Let me get this. Correct me if I am wrong. It seems that you want
> to use 64bit registers in an o32 binary. Am I right?
Uh, the way you phrase that, i get the feeling that you think i'm
silly for saying "yes." But I think that's probably only because you
structure the question unfavforably. I don't think I said anything
about "an o32 binary," just a 32-bit ELF binary.
"mips64-elf" tools have, historically, generated:
* 32-bit ELF
* mips3-compatible code (including use of full 64-bit GPRs).
Unless you say -mlong64, pointers and longs will be 32-bit, but you'll
use full 64-bit GPRs for 'long long'.
If you do say -mlong64, you'll get 64-bit pointers and longs, in your
All with a 32-bit ELF format. (And, using R_MIPS_64 to represent
pointers in the object files.)
I don't really _know_ what ABI it uses. I had always thought of it as
"o64", which in my mind was "o32 naively extended for 64-bit GPRs,"
but really i don't know that that's correct. In fact, I don't really
_care_ what ABI it uses. We understand the calling conventions well
enough for embedded development use, which is where we're using it.
In any case, it _does_ work (or did until recently -- i've not really
tried in the last few months with a truly vanilla mips64-elf
configuration, since we've got a clone of mips64-elf with a few minor
mods which are irrelevant for the purposes of this discussion 8-).
You can be sure that if we are, there's no shortage of others doing so