From: "Timothy A. Seufert" <tas@mindspring.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Neil Russell <caret@c-side.com>,
David Riley <oscar@the-rileys.net>,
linuxppc-dev@lists.linuxppc.org
Subject: Re: PPC byte ordering
Date: Tue, 31 Oct 2000 03:23:01 -0800 [thread overview]
Message-ID: <v04220801b6245b031367@[10.0.0.42]> (raw)
In-Reply-To: <Pine.LNX.4.10.10010301315510.413-100000@cassiopeia.home>
At 1:18 PM +0100 10/30/00, Geert Uytterhoeven wrote:
>On Mon, 30 Oct 2000, Timothy A. Seufert wrote:
>> At 5:24 PM -0700 10/28/00, Neil Russell wrote:
>> >It would in theory be possible to have the kernel run big-endian as it is
>> >and have certain user programs run little endian by setting the LE bit in
>> >the MSR register for the process in question. The real problem here is
>> >that you have to add a *lot* of code to system calls to make this work.
>> >There are a few system calls that this would be real difficult, such
>> >as ioctl(). I once looked into doing this for the MIPS with SVR4 UNIX.
>>
>> The other real problem is that Linus Torvalds has already said that
>> he will never ever in a million years accept a patch which attempts
>> to do such a thing, so you'd have to fork the kernel to do it.
>> According to Linus, architectures are either big or little-endian,
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> not both. A sane position considering the syscall ugliness you
> ^^^^^^^^^
>> mention...
>
>Really? Or did he mean: big-endian kernels must not run little-endian binaries
>and vice versa.
>
>Note that there exist 3 flavors of MIPS: 32-bit big-endian, 32-bit
>little-endian and 64-bit. Linux supports them all. Expect to upgrade the hard
>drives on your local Debian mirror soon :-)
You're absolutely correct -- what he doesn't want (at least as I
interpreted the email I'm remembering from a linux-kernel discussion)
is mixing modes. In other words, the official Linus kernel will
never support mixed LE and BE processes at runtime; you must choose
one or the other at kernel compile time.
Tim Seufert
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
prev parent reply other threads:[~2000-10-31 11:23 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-10-28 20:50 PPC byte ordering David Riley
2000-10-29 0:24 ` Neil Russell
2000-10-30 9:12 ` Timothy A. Seufert
2000-07-19 13:59 ` Heiko Jakob
2000-10-30 12:50 ` Gabriel Paubert
2000-10-30 12:18 ` Geert Uytterhoeven
2000-10-31 11:23 ` Timothy A. Seufert [this message]
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