Re: 64 bits Kernel and 32 bits process
Re: 64 bits Kernel and 32 bits process
- Subject: Re: 64 bits Kernel and 32 bits process
- From: Stéphane Sudre <email@hidden>
- Date: Mon, 17 Jan 2005 17:10:37 +0100
On Jan 17, 2005, at 5:06 PM, Shawn Erickson wrote:
On Jan 17, 2005, at 7:40 AM, Stéphane Sudre wrote:
Is there a documentation explaining somewhere very clearly how a 32
bits process is running in a 64 bits capable OS?
Because I'm wondering what kind of address is ok for copyin when the
address-space in the kernel is 64 bits.
I have some problem understanding how providing my user space address
from a 32 bits process is going to work in every case when the
address space can be 64 bits. Unless 32 bits processes can't be
executed in the last 32 bits of the 64 bits address space.
Hint and aspirin welcome.
In current Mac OS X (aka Darwin) neither kernel space nor user space
supports 64b address spaces. Additionally the stated intention for Mac
OS X going forward is to always have one kernel version for Mac OS X
which runs in a 32b address space while adding the ability to run
processes in either a 32b or 64b address space.
So on current Mac OS X you are always working with 32b addresses
(unless you are some how hacking into the VM system which has the
ability to map physical memory greater then 32b allows).
For info on how Mac OS X supports greater then 4GB of physical RAM
while still maintaining a 32b kernel, etc...
<http://developer.apple.com/technotes/tn/tn2090.html>
Basic info about future 64b addressing support in Mac OS X...
This is the one I read and it didn't help.
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