Date: Thu, 10 Jun 2004 13:24:57 -1000 From: juli mallett <jmallett@FreeBSD.org> To: Ralf Baechle <ralf@linux-mips.org> Cc: "Steffen M. Boelaars" <boelaars@graphicscave.com> Subject: Re: Some MIPS status goodies. Message-ID: <20040610232457.GA31150@FreeBSD.org> In-Reply-To: <20040610231904.GB16814@linux-mips.org> References: <Pine.LNX.4.33.0406101040240.2858-100000@servww6.ww.uni-erlangen.de> <20040610090712.GA71925@FreeBSD.org> <4038.217.68.50.10.1086861511.squirrel@webmail.dataloss.nl> <20040610101801.GA75709@FreeBSD.org> <20040610123718.GA32315@linux-mips.org> <20040610221746.GB26579@FreeBSD.org> <20040610231904.GB16814@linux-mips.org>
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* Ralf Baechle <ralf@linux-mips.org> [ Date: 2004-06-10 ]
[ w.r.t. Re: Some MIPS status goodies. ]
> On Thu, Jun 10, 2004 at 12:17:46PM -1000, juli mallett wrote:
>
> > > 64-bit ELF requires very recent GNU tools and even in those it cannot
> > > be considered of prime quality.
> >
> > Right now I'm struggling with the more loathsome problem of
> > elf<mumble>-{,trad}{big,little}mips ... Just where do you and don't
> > you need the "trad" -- this seems to be a painful thing, certainly
> > it has been for me, and I'm hoping that BU (namely BFD) will grow
> > some more friendly compilation conditionals in the future, but I'm
> > not going out of my way for that... Certainly I'm happy with my
> > working elf32-tradbigmips toolchain.
>
> >From my experience forget about the non-trad variant. trad*mips is ABI
> ELF (or rather ABI ELF with GNU breakage); the non-trad variants are
> IRIX ELF with it's undocumented differences compared to ABI ELF. The
> nasty stuff about IRIX ELF is that some of it's difference also affect
> generic ELF.
>
> We used to use non-trad ELF for Linux until we hit a problem with modutils
> which was explained by the difference between non-trad ELF and trad ELF,
> so we switched. I think this is the only time the difference between the
> two actually did matter to us.
non-trad elf has a lot of problems. But just having trad stuff, while fine
for config.bfd, seems to cause havoc with the BU build environment FreeBSD
uses and I can't figure out what's up. I get some of BU's lovely obscure
messages there which make me think something is very borked.
The non-trad stuff, in 64 bit mode, also wants stuff like rld_map which I am
fundamentally opposed to adding.
> > > 64-bit code is so much larger that it often delivers just half the
> > > performance of 32-bit code.
> >
> > FreeBSD/MIPS is definably 64-bit code, just 32-bit ELF for now.
>
> Ah, that sounds like the hack which I'm using also. Initially born due
> to the complete unusability of NABI ELF this code model turned into the
> code model of choice because it's so much more efficient and smaller -
> the difference is in the range of hundreds of kB for an IP27 kernel.
> The problem is this may become impossible with later GNU tools but let's
> see what can be done about that.
Works well enough as long as you have CKSEG around :( (or a sufficiently
complex bootloader and simple enough system that you can cheat and run it
out of user address space.)
--
juli mallett. jmallett@freebsd.org. adrift in the pacific.
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