From: "Andreas K. Hüttel" <dilfridge@gentoo.org>
To: libc-alpha@sourceware.org, joseph@codesourcery.com
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Subject: Re: RISC-V 64bit and 32bit binaries on the same system
Date: Wed, 09 Sep 2020 22:49:51 +0300 [thread overview]
Message-ID: <5977652.RfpFWEtPUA@farino> (raw)
In-Reply-To: <mhng-07bac7fe-a215-4a1b-9d4f-4672cdfd7482@palmerdabbelt-glaptop1>
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> > (And it looks like a comparatively large amount of work for a situation
> > that is right now fairly hypothetical, unless you try silly things with
> > qemu like me).
>
> It'd be great to bootstrap all the multilib stuff, but it's just a matter of
> priorities. It's a fairly large amount of work to put this all together,
> but it shouldn't be all that hard to add writable XLEN to QEMU which would
> allow Linux to spin up rv32 processes. There'd be a big pile of work left
> at that point, though...
Well it kinda-works half in a Gentoo qemu-user chroot right now, which is of
course not the most useful production environment. :)
What looks good in my experiments:
* building and installing gcc with all 4 ABI and multilib paths
* building and installing glibc with all 4 ABI and multilib paths
Then, the Gentoo multilib system still works *if* I order the ld.so search
paths right (all the executables are lp64d, so that comes first, and the
ilp32[d] libs are ignored). All four ld.so variants are installed.
In principle, *if* ld.so were to ignore wrong elfclass (with all changes that
this requires), a mixed multilib Gentoo install could work more or less out of
the box. We already use /usr/lib64/lp64[d], and I hook into the same path
adjustment mechanisms and multi-abi builds we have made for x86-64/i686 and
others.
> > So maybe the multilib defaults of gcc should be changed?
>
> Either way, that seems reasonable to me. If we ever implement it we can
> always add the multilibs back, but it doesn't seem reasonable to default to
> something broken. I bet you guys are the first to take a shot at the Linux
> multilib stuff, so I anticipate a bunch of stuff will be broken.
>
> Do you want to send a GCC patch, or do you want me to?
I agree; we can always slowly prepare the support anyway so it's ready once
there is hardware.
It's probably better if the gcc patch comes from you ("more official").
Best,
Andreas
--
Andreas K. Hüttel
dilfridge@gentoo.org
Gentoo Linux developer
(council, qa, toolchain, base-system, perl, libreoffice)
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prev parent reply other threads:[~2020-09-09 19:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-07 13:32 Andreas K. Hüttel
2020-09-07 16:56 ` Joseph Myers
2020-09-07 17:05 ` Andreas K. Hüttel
2020-09-09 4:22 ` Palmer Dabbelt
2020-09-09 19:49 ` Andreas K. Hüttel [this message]
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