Date: Tue, 07 May 2002 23:28:37 -0700 From: Peter Wemm <peter@wemm.org> To: Nathan Hawkins <utsl@quic.net> Cc: arch@FreeBSD.ORG Subject: Re: syscall changes to deal with 32->64 changes. Message-ID: <20020508062837.696D738CC@overcee.wemm.org> In-Reply-To: <3CD823E8.2010809@quic.net>
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Nathan Hawkins wrote:
> David O'Brien wrote:
>
> >On Tue, May 07, 2002 at 12:18:31PM -0400, Nathan Hawkins wrote:
> >
> >
> >>I'd like to see FreeBSD start using ELF .note.ABI-tag sections to handle
> >>the binary OS type/versioning. I know that at least NetBSD, Linux and
> >>Hurd do it this way, and I think most others do too.
> >>
> >>
> >
> >Why? Just to follow the NIH herd? The EI_OSABI and EI_ABIVERSION fields
> >were in the gABI spec before anyone started using .note sections for
> >this.
> >
> >
> Because AFAICS, it's a defacto, unwritten standard. Even if it violates
> spec.
>
> NIH is a matter of perspective. FreeBSD could be considered to be in NIH
> mode, because the other ELF based systems use a different method.
I seem to recall that NetBSD invented .note.ABI-tag and pushed it back
to the binutils folks. In a later revision of ELF, the EI_OSABI stuff
was added. .note.ABI-tag predated those additions. When FreeBSD first
started dabbling with ELF, the NetBSD folks were tinkering with the
.note (and PT_NOTE executable header) stuff, and Linux had a "personality"
syscall. For linux, ELF executables started up in "SVR4 mode" and the
personality syscall changed it to "linux". (SYS_personality was a syscall
number that didn't exist on SVR4). We didn't do *anything* with note
sections till much much later on.
We still have an emulation stub for it.. see sys/compat/linux/linux_misc.c
/*
* UGH! This is just about the dumbest idea I've ever heard!!
*/
int
linux_personality(struct thread *td, struct linux_personality_args *args)
{
#ifdef DEBUG
if (ldebug(personality))
printf(ARGS(personality, "%d"), args->per);
#endif
#ifndef __alpha__
if (args->per != 0)
return EINVAL;
#endif
/* Yes Jim, it's still a Linux... */
td->td_retval[0] = 0;
return 0;
}
Cheers,
-Peter
--
Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5
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