Re: [Xen-devel] HPET enabled in BIOS, not presented as available_clocksource -- config, kernel code, &/or BIOS?

[Randy Dunlap <rdunlap@xxxxxxxxxxxxx>]

On 05/14/17 08:39, Andrew Cooper wrote:
> On 14/05/17 00:17, PGNet Dev wrote:
>> On 5/13/17 3:15 PM, Valentin Vidic wrote:
>>> Try booting without 'hpet=force,verbose clocksource=hpet' and it should
>>> select xen by default:
>> Nope. Well, not quite ...
>>
>> With both 
>>
>>      'hpet=force,verbose clocksource=hpet'
>>
>> removed, I end up with
>>
>>      cat /sys/devices/system/clocksource/clocksource0/available_clocksource
>>              tsc xen
>>      cat /sys/devices/system/clocksource/clocksource0/current_clocksource
>>              tsc
>>
>> But with 
>>
>>      clocksource=xen
>>
>> *explicitly* added
>>
>>      cat /sys/devices/system/clocksource/clocksource0/available_clocksource
>>              tsc xen
>>      cat /sys/devices/system/clocksource/clocksource0/current_clocksourcexen
>>              xen
>>
>> and in *console*, NOT dmesg, output,
>>
>>      grep -i hpet tmp.txt
>>              (XEN) ACPI: HPET 9E8298F8, 0038 (r1 SUPERM SMCI--MB  1072009 
>> AMI.        5)
>>              (XEN) ACPI: HPET id: 0x8086a701 base: 0xfed00000
>>              (XEN) [VT-D] MSI HPET: 0000:f0:0f.0
>>              (XEN) Platform timer is 14.318MHz HPET
>>              [    0.000000] ACPI: HPET 0x000000009E8298F8 000038 (v01 SUPERM 
>> SMCI--MB 01072009 AMI. 000000
>>              [    0.000000] ACPI: HPET id: 0x8086a701 base: 0xfed00000
>>              [    0.000000] ACPI: HPET 0x000000009E8298F8 000038 (v01 SUPERM 
>> SMCI--MB 01072009 AMI. 000000
>>              [    0.000000] ACPI: HPET id: 0x8086a701 base: 0xfed00000
>>              [    8.515245] hpet_acpi_add: no address or irqs in _CRS
>>              [    8.515245] hpet_acpi_add: no address or irqs in _CRS
>>              (XEN) [2017-05-13 23:04:27] HVM1 save: HPET
>>
>>
>>
>> and
>>
>>      dmesg | grep -i clocksource | grep -v line:
>>              [    0.000000] clocksource: refined-jiffies: mask: 0xffffffff 
>> max_cycles: 0xffffffff, max_idle_ns: 7645519600211568 ns
>>              [    0.004000] clocksource: xen: mask: 0xffffffffffffffff 
>> max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns
>>              [    0.375709] clocksource: jiffies: mask: 0xffffffff 
>> max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
>>              [    4.656634] clocksource: Switched to clocksource xen
>>              [    8.912897] clocksource: tsc: mask: 0xffffffffffffffff 
>> max_cycles: 0x2c94dffea94, max_idle_ns: 440795361700 ns
>>
>> jiffies, now? hm. no idea where that came from. and why the 'tsc' ?
>>
>> So I'm still unclear -- is this^ now, correctly "all" using MSI/HPET?
> 
> What are you trying to achieve?  It is still not clear despite all on
> this thread.

I agree.  Are you (pgnet.dev) just curious about why the Xen kernel does
not expose HPET as a clocksource or is not having it causing some problem
for you or some specific software application?


> The Linux HEPT error messages are non-ideal, but there is no way dom0
> will ever be able to use clocksource=hpet when running under Xen.



-- 
~Randy

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