Question regarding HPET the 2.6 series kernel.

Question regarding HPET the 2.6 series kernel.

[Justin Piszcz]

[*] HPET Timer Support
[*]   Provide RTC interrupt

[*] HPET - High Precision Event Timer
[*]   Allow mmap of HPET

http://tlug.up.ac.za/guides/lkcg/arch_i386.html

HPET Timer Support	HPET_TIMER
This enables the use of the HPET for the kernel's internal timer. HPET is 
the next generation timer replacing legacy 8254s. You can safely choose Y 
here. However, HPET will only be activated if the platform and the BIOS 
support this feature. Otherwise the 8254 will be used for timing services. 
Choose N to continue using the legacy 8254 timer.

How do I determine if my BIOS has this feature?

$ dmesg | grep -i hpet
$ dmesg | grep -i 8254
$ dmesg | grep -i timer
..TIMER: vector=0x31 pin1=2 pin2=-1
PCI: Setting latency timer of device 0000:02:01.0 to 64
$

Assuming it does, is there any reason to use or not to use this feature?

Thanks,

Justin.

RE: Question regarding HPET the 2.6 series kernel.

[Pallipadi, Venkatesh]

When it is supported in BIOS, you will see a HPET line similar to below
in initial ACPI messages.

ACPI: OEMB (v001 A M I  AMI_OEM  0x05000510 MSFT 0x00000097) @
0xdffdf040
ACPI: HPET (v001 A M I  OEMHPET  0x05000510 MSFT 0x00000097) @
0xdffd7480


And when it is supported in BIOS, kernel always uses it.

Thanks,
Venki
  

>-----Original Message-----
>From: linux-kernel-owner@vger.kernel.org 
>[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Justin Piszcz
>Sent: Sunday, August 14, 2005 3:22 AM
>To: linux-kernel@vger.kernel.org
>Subject: Question regarding HPET the 2.6 series kernel.
>
>
>[*] HPET Timer Support
>[*]   Provide RTC interrupt
>
>[*] HPET - High Precision Event Timer
>[*]   Allow mmap of HPET
>
>http://tlug.up.ac.za/guides/lkcg/arch_i386.html
>
>HPET Timer Support	HPET_TIMER
>This enables the use of the HPET for the kernel's internal 
>timer. HPET is 
>the next generation timer replacing legacy 8254s. You can 
>safely choose Y 
>here. However, HPET will only be activated if the platform and 
>the BIOS 
>support this feature. Otherwise the 8254 will be used for 
>timing services. 
>Choose N to continue using the legacy 8254 timer.
>
>How do I determine if my BIOS has this feature?
>
>$ dmesg | grep -i hpet
>$ dmesg | grep -i 8254
>$ dmesg | grep -i timer
>..TIMER: vector=0x31 pin1=2 pin2=-1
>PCI: Setting latency timer of device 0000:02:01.0 to 64
>$
>
>Assuming it does, is there any reason to use or not to use 
>this feature?
>
>Thanks,
>
>Justin.
>
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