From: Rusty Russell <rusty@rustcorp.com.au>
To: Richard Weinberger <richard@nod.at>, linux-kernel@vger.kernel.org
Cc: x86@kernel.org, rostedt@goodmis.org, jbaron@redhat.com,
akpm@linux-foundation.org, vapier@gentoo.org,
user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [RFC] UML/x86_64 module loader
Date: Tue, 23 Aug 2011 13:22:18 +0930 [thread overview]
Message-ID: <878vqk4wel.fsf@rustcorp.com.au> (raw)
In-Reply-To: <4E52CC63.5070201@nod.at>
On Mon, 22 Aug 2011 23:38:43 +0200, Richard Weinberger <richard@nod.at> wrote:
> Hi!
>
> UserModeLinux is using the arch specific module functions from
> arch/x86/kernel/module.c.
> On i386 this works perfectly fine but on x86_64 it causes problems.
>
> apply_relocate_add() assumes modules compiled with -mcmodel=kernel
> because the kernel lives in the negative 2GiB of the address space.
> This assumption is not true for UML.
> On an UML instance with more than 512MiB of memory no modules can be
> loaded because vmalloc() locates the module near the 2GiB limit and the
> ELF relocations causes an overflow. (Detected by "if ((s64)val != *(s32
> *)loc)" in apply_relocate_add()).
>
> Now I'm not sure how to fix this.
> Mostly because I'm not a module loader nor an ELF expert. 8-)
I think you need to write your own routines. It shouldn't be that hard,
just keep implementing relocations until you're done :)
Cheers,
Rusty.
prev parent reply other threads:[~2011-08-23 3:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-22 21:38 [uml-devel] [RFC] UML/x86_64 module loader Richard Weinberger
2011-08-22 21:38 ` Richard Weinberger
2011-08-23 3:52 ` Rusty Russell [this message]
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