Re: [PATCH] [AArch64] Define BE loader name.

[Steve McIntyre <steve dot mcintyre at linaro dot org>]

[ I hope this threads OK - replying to the thread using the list
  archives... ]

Carlos wrote:
>
>We need technical arguments from both sides to reach consensus.
>
>Marcus has to come up with real reasons for needing the new dynamic
>linker name.

Carlos already contributed to a ML discussion that happened after
Linaro Connect in November last year, where we had broad consensus
from the distros about separating the dynamic linker names for BE and
LE systems:

  http://lists.linaro.org/pipermail/cross-distro/2013-November/000570.html

As a background to that, I'm the team lead for Big Endian work in the
Linaro Networking Group (LNG). For a variety of reasons we're working
on supporting both BE and LE code on a single system and we're
investigating various options. Yes, it's a *horrible* idea but there
are people who really want to use this. I can envisage places where we
may want to have have both BE and LE binaries co-existing in the same
system, and it would be nice if that's not locked out here.

I'll be honest: I *don't* think that the general purpose Linux distros
are likely to care about BE ARM or AArch64 systems in the same way as
us, but who knows what might come up?

>Andrew, you need to come up with concrete reasons for not wanting to
>use a symlink or a copy.
>
>This is *exactly* the same kind of change we made for the 32-bit ARM
>hard-float dynamic linker name change.

Yup, Been there, done that. In future, would it not make sense in
general to try and keep dynamic linkers separated by default?

>The only wrinkle is that a symlink doesn't actually work:
>https://sourceware.org/ml/libc-alpha/2012-10/msg00670.html
>
>If Markus is suggesting using a symlink he'll have to look into the
>problem I posted, because the last time I checked the symlink setup
>didn't work and required a hack to be used until all binaries had
>been migrated.

Yup. :-( I remember the hack I came up with, and I've pointed Marcus
at it to help him understand what we did and why:

  http://anonscm.debian.org/viewvc/pkg-glibc/glibc-package/trunk/debian/patches/arm/local-soname-hack.diff?view=markup

>Thankfully in the case of the hard-float dynamic linker name change
>we had consensus that the name change was needed to support a mixed
>environment.

Right.

Cheers,
-- 
Steve McIntyre                                steve.mcintyre@linaro.org
<http://www.linaro.org/> Linaro.org | Open source software for ARM SoCs