Re: [Qemu-devel] ix64 target support

From: Karl Magdsick <kmagnum@gmail.com>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] ix64 target support
Date: Tue, 28 Sep 2004 16:58:12 -0400	[thread overview]
Message-ID: <cd8ecdef0409281358425658a3@mail.gmail.com> (raw)
In-Reply-To: <1096390325.4234.365.camel@fred.soliddesign.net>

There is the ia64 architecture (Itanium) and the amd64 architecture
(Opteron, Athlon64, formerly known as x86_64).  (The Linux kernel
still uses the old architecture name, but some linux (??most??)
distributions have adopted the manufacturer's official name for the
architecture.)

I assume you're talking about amd64.

QEMU is capable of emulating PPC on x86, so the extra number of
registers on amd64 as opposed to x86 is not an issue.  Each 64 bit
register would, of course have to be treated as a pair of 32-bit
registers on 32-bit platforms, of course.

I have read that QEMU does not emulate the MMU (at least with some
target/host combinations), but you will probably need to emulate a
64-bit MMU on 32-bit platforms.  (Actually, I've read that current
amd64 chips actually use 40-bit addressing internally, so you only
need to emulate a 40-bit MMU.  I would personally not intentionally
emulate the limitations of the current batch of chips if the processor
family clearly is intended to go beyond these limitations in the
future.)

While we're on the subject of future plans for QEMU, I've read that
QEMU makes no attempts at optimal register allocation.  Are there
plans to change this in the future?  I've heard the arguments about
debugging, but I've heard that debuggers are refusing to debug the
translated code anyway.

Cheers,
-Karl

On Tue, 28 Sep 2004 11:52:05 -0500, Joe Batt <joe@soliddesign.net> wrote:
> I have a project that I'd like to code for 64 bit memory addressing (big
> pointers).  I will eventually purchase 64 bit equipment, but I'd like to
> do a feasibility test first.
> 
> qemu doesn't yet support a ix64 target.  How far are we from that?  Is
> anyone working on it?  Is it as simple as implementing some extra
> opcodes or are there fundamental issues?
> 
> I've implemented a simple sh2 emulator in a previous project; I
> understand just a little of how qemu might work.  I may be able to help.
> 
> Thanks,
> Joe
> 
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