The following operating systems are known
not to be able to use HPET: Windows XP,[note 2] Windows Server 2003, and earlier Windows versions, Linux kernels prior to 2.6.[note 3]
The following operating systems are known to be able to use HPET: Windows XP SP3,[note 4] Windows Server 2008, Windows Server 2008 R2, Windows Vista, Windows 7, x86 based versions of Mac OS X, Linux operating systems using the 2.6 kernel (or later), FreeBSD[clarification needed][citation needed] and OpenSolaris.[citation needed]