Editing Physical Address Extension (section)

== Hardware support ==
{{see also|CPUID}}

Software can identify via the <code>[[CPUID]]</code> flag <code>PAE</code> whether a CPU supports PAE mode or not. A free-of-charge program for Microsoft Windows is available which will list many processor capabilities, including PAE support.<ref>{{cite web|url=https://learn.microsoft.com/en-us/sysinternals/downloads/coreinfo |title=Coreinfo - Sysinternals |work=Windows Sysinternals |publisher=Microsoft |date=7 June 2023 |access-date=11 July 2023}}</ref> In Linux, commands such as <code>cat /proc/cpuinfo</code> can list the <code>pae</code> flag when present,<ref>{{cite web | title = Detecting your Hardware | publisher = Gentoo | date = October 8, 2008 | url = http://www.gentoo-wiki.info/Detecting_your_Hardware | access-date = 2013-04-28 |archive-url=https://web.archive.org/web/20130503041154/http://www.gentoo-wiki.info/Detecting_your_Hardware#.2Fproc.2Fcpuinfo |archive-date=2013-05-03 |url-status=usurped}}</ref> as well as other tools such as the [[SYSLINUX]] Hardware Detection Tool.

To run the processor in PAE mode, [[operating system]] support is required. To use PAE to access more than 4 GB of RAM, further support is required in the operating system, in the chipset, and on the motherboard. Some chipsets do not support physical memory addresses above 4 GB (FFFFFFFF in hexadecimal), and some motherboards simply do not have enough RAM sockets to allow the installation of more than 4 GB of RAM. Nevertheless, even if no more than 4 GB of RAM is available and accessible, a PAE-capable CPU may be run in PAE mode, for example to allow use of the [[No execute]] feature.