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Re: [Qemu-devel] [PATCH v2 5/5] linux-user: Add aarch64_be magic numbers
From: |
Laurent Vivier |
Subject: |
Re: [Qemu-devel] [PATCH v2 5/5] linux-user: Add aarch64_be magic numbers to qemu-binfmt-conf.sh |
Date: |
Wed, 20 Dec 2017 17:43:34 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 |
Le 20/12/2017 à 17:15, Michael Weiser a écrit :
> Hi Laurent,
>
> On Wed, Dec 20, 2017 at 04:56:41PM +0100, Laurent Vivier wrote:
>
>>> Based on that I suspect that qemu-binfmt-conf.sh's current assignment of
>>> armeb and aarch64 into the arm CPU family is over-optimistic as well.
>>> So I'd suggest treating all of arm, armeb, aarch64 and aarch64_be as
>>> separate families.
>> So it's not like on intel/AMD where we can execute a 32bit binary on a
>> 64bit kernel?
>
> An aarch64 CPU is capable of running arm (i.e. aarch32) code. And I
> think this is supported as a multilib setup on Linux. But not in mixed
> endianess as far as I know.
>
> Looking at the code again, I'm confused now: Wouldn't the current logic
> treat an actual i386 machine as capable of running x86_64 binaries
> natively and omit registering the handler for x86_64?
It can be read like that, but actually 32bit machine cannot emulate
64bit architecture, so we don't register it.
So for the same family:
- on 64bit machine, we don't register the interpreter because the 32bit
binary can be executed natively,
- on 32bit machine, we don't register the interpreter because the
interpreter cannot work,
Thanks,
Laurent
[Qemu-devel] [PATCH v2 4/5] configure: Add aarch64_be-linux-user target, Michael Weiser, 2017/12/19
Re: [Qemu-devel] [PATCH v2 0/5] Add aarch64_be-linux-user target, no-reply, 2017/12/21