HPET: Difference between revisions
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:''This page is not meant as a full description of HPET, only as a lightweight introduction. If you need any information not covered by this article, consult the [http://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/software-developers-hpet-spec-1-0a.pdf HPET specification].'' |
:''This page is not meant as a full description of HPET, only as a lightweight introduction. If you need any information not covered by this article, consult the [http://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/software-developers-hpet-spec-1-0a.pdf HPET specification].'' |
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'''HPET''', or High Precision Event Timer, is a piece of hardware designed by Intel and Microsoft to replace older [[PIT]] and [[RTC]]. It consists of (usually 64-bit) main counter (which counts up), as well as from 3 to 32 32 or 64 |
'''HPET''', or High Precision Event Timer, is a piece of hardware designed by Intel and Microsoft to replace older [[PIT]] and [[RTC]]. It consists of (usually 64-bit) main counter (which counts up), as well as from 3 to 32 32-bit or 64-bit wide comparators. HPET is programmed using memory mapped IO, and the base address of HPET can be found using [[ACPI]]. |
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==Detecting HPET using ACPI== |
==Detecting HPET using ACPI== |
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The [http://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/software-developers-hpet-spec-1-0a.pdf HPET specification] defines an ACPI 2.0 table that is to be used to detect presence, address and capabilities of HPET present in the system. If this table doesn't exist, you should assume there is no HPET and you should fall back to PIT. |
The [http://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/software-developers-hpet-spec-1-0a.pdf HPET specification] defines an ACPI 2.0 table that is to be used to detect presence, address and capabilities of HPET present in the system. If this table doesn't exist, you should assume there is no HPET and you should fall back to [[PIT]] or the [[APIC timer]]. |
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==See also== |
==See also== |
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* [[IOAPIC]] |
* [[IOAPIC]] |
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* [[APIC]] |
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* [[APIC timer]] |
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* [[PIT]] |
* [[PIT]] |
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* [[RTC]] |
* [[RTC]] |
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