From mboxrd@z Thu Jan 1 00:00:00 1970 Message-Id: <9904021711.AA35268@marc.watson.ibm.com> To: Holger Bettag Cc: linuxppc-dev@lists.linuxppc.org Subject: Re: Apple Job Posting and Good News for LinuxPPC developers In-Reply-To: Message from Holger Bettag of "02 Apr 1999 14:11:16 +0200." <8x677fp6hn.fsf@s52.informatik.uni-bremen.de> Date: Fri, 02 Apr 1999 12:11:12 -0500 From: David Edelsohn Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: >>>>> Holger Bettag writes: Holger> I have heard rumours that the "Max" core has provisions to physically address Holger> more than 4GB of memory (via the MMU's segment registers). Processes would Holger> still be limited to a 4GB logical address space, though. The PowerPC architecture always has been able to address more than 32-bits of "logical" address space. That is the reason for the PowerPC terminology of "effective address", "virtual address", and "real address". The intermediate "virtual address" space of a 32-bit PowerPC implementation is 52 bits. Pointers still are 32-bits, but a cooperating operating system and compiler can allow an application to address more virtual memory through runtime modifications to the virtual segments mapped by the segment registers, like memory overlays. That was the original reason for the design of the MMU in the POWER (predecessor of PowerPC) architecture. I do not believe that any compiler / OS combination takes advantage of this facility. David [[ This message was sent via the linuxppc-dev mailing list. Replies are ]] [[ not forced back to the list, so be sure to Cc linuxppc-dev if your ]] [[ reply is of general interest. Please check http://lists.linuxppc.org/ ]] [[ and http://www.linuxppc.org/ for useful information before posting. ]]