org/
Oszoo: http://www.oszoo.org/wiki/index.php/Category:OS_images
Physical Address Extension
Physical Address Extension (PAE) is a technology that increases the amount of
physical or virtual memory available to user mode applications and thus allows
servers to access physical memory beyond 4 GB. In order to achieve this, PAE
modifies the 32-bit addressing mode to a 64-bit addressing mode, and thus allows
the operating system and user applications to access the additional physical memory.
This can significantly enhance the performance of the operating system, which is
valuable especially when the server is hosting multiple operating systems. Both the
Linux kernel and the Xen hypervisor can benefit from of PAE if it is present. The
three modes that are available for running Xen are as follows:
Pure 32-bit mode.
32-bit mode with PAE.
Pure 64-bit mode.
There are some important things to consider when using these modes:
The Xen hypervisor, dom0, and domU must run in the same mode when
using paravirtualization. This means that when using paravirtualization, if
the hypervisor is running in 32 bit mode, then the dom0 and all the domU
instances must also run in the 32 bit mode, and not in the PAE or 64 bit
modes. You cannot currently mix and match different modes of Xen.
The above restriction does not apply when using full virtualization or
Hardware Virtual Machine (HVM). Currently you can only use HVM with
supported chipsets from Intel and AMD.
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