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

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Date:   Sat, 13 May 2017 21:45:12 +0200
From:   Clemens Ladisch <clemens@...isch.de>
To:     pgnet.dev@...il.com
Cc:     Randy Dunlap <rdunlap@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: HPET enabled in BIOS, not presented as available_clocksource --
 config, kernel code, &/or BIOS?

Randy Dunlap wrote:
> On 05/12/17 19:30, PGNet Dev wrote:
>> 	dmesg | grep -i hpet
>> 		[    8.491738] hpet_acpi_add: no address or irqs in _CRS
>
> Above line marks a big failure. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>> Disassembling the firmware acpi tables
>>
>> 	cat /sys/firmware/acpi/tables/HPET > /var/tmp/hpet.out
>> 	iasl -d /var/tmp/hpet.out

That table is not used by hpet_acpi_add; you have to check for the device
that mentions "PNP0103" in the DSDT table.

But anyway, as far as I can tell from my own machine, the _CRS in the
DSDT table never lists the HPET interrupts, and the HPET registration is
always done by hpet_reserve_platform_timers() in arch/x86/kernel/hpet.c.
Try adding logging to hpet_late_init() to find out why it aborts.

Regards,
Clemens