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

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Message-ID: <34c505d9-9dc6-8982-4875-74dedfc5e0d1@gmail.com>
Date:   Sat, 13 May 2017 12:49:32 -0700
From:   PGNet Dev <pgnet.dev@...il.com>
To:     Andrew Cooper <andrew.cooper3@...rix.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Clemens Ladisch <clemens@...isch.de>,
        xen-devel@...ts.xenproject.org
Subject: Re: [Xen-devel] HPET enabled in BIOS, not presented as
 available_clocksource -- config, kernel code, &/or BIOS?

On 5/13/17 12:38 PM, Andrew Cooper wrote:
> What is the issue here?
> 
> Xen owns (and may use) any HPETs in the system.  They are purposefully
> unavailable to even dom0.

The issue is that, when booting to Xen, hpet is not advertised as an available clocksource, AND reports the hpet boot error pointed out by Randy.

Following 

  https://wiki.xen.org/wiki/Xen_power_management#HPET_as_broadcast_timer_source_.28clocksource.29_.3D

there's discussion there re: 'if HPET is available / not missing'.

It appears to be available only booting to non-Xen.

What specific indication does one look for that Xen's using available hpet?