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Re: [Qemu-devel] [PATCH, RFC] More than 2G of memory on 64-bit hosts

From: Thiemo Seufer
Subject: Re: [Qemu-devel] [PATCH, RFC] More than 2G of memory on 64-bit hosts
Date: Tue, 26 Jun 2007 09:00:36 +0100
User-agent: Mutt/1.5.13 (2006-08-11)

Karl Magdsick wrote:
> With proper support from the compiler, it's theoretically possible on
> x86-64 systems to use 32-bit pointers in long mode (16 general purpose
> 64-bit registers).  (There's an instruction prefix that will cause the
> CPU to perform 32-bit pointer calculations in the 64-bit address
> space.) I'm not aware of any systems that use this, however.  (Getting
> the speed boost from fewer register spills while not paying the space
> cost of 64-bit pointers sounds very attractive in many applications,
> though.)

FYI, the MIPS N32 ABI does that (64bit wide registers, 32bit address
space, data type sizes compatible to pure 32bit programs).


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