Thread (170 messages) flat view 170 messages, 19 authors, 2012-09-16

[PATCH v2 16/31] arm64: ELF definitions

From: Mike Frysinger <hidden>
Date: 2012-08-21 18:53:21
Also in: linux-arch, lkml

On Tuesday 21 August 2012 14:27:31 Catalin Marinas wrote:
On Tue, Aug 21, 2012 at 07:17:19PM +0100, Geert Uytterhoeven wrote:
quoted
On Tue, Aug 21, 2012 at 6:06 PM, Catalin Marinas wrote:
quoted
But I can see on x86 that it always reports x86_64 even if the task is
x86_32.
Really?

$ uname -m
x86_64
$ linux32 uname -m
i686
$
Well, you set the personality explicitly with linux32. What I tested was
with an x86_32 uname called directly (without linux32) and even though
the ELF was a 32-bit one, it was reporting x86_64. In this AArch64
patch, a compat task was automatically setting the linux32 personality
(which x86 does not do).
i don't think any arch does this.

$ uname -m
ppc64
$ linux32 uname -m
ppc

$ uname -m
sparc64
$ linux32 uname -m
sparc

$ uname -m
x86_64
$ linux32 uname -m
i686

$ uname -m
s390x
$ linux32 uname -m
s390
Arnd's point is that the ELF file should not affect the personality and
hence the uname value. This should only be done by an explicit call to
sys_personality().
correct.  if someone really wants to launch their whole userland with the 
adjusted personality, they could always boot the kernel with:
	init=/usr/bin/linux32 /sbin/init
but the kernel shouldn't be doing this automatically.
-mike
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