linux-kernel - Re: [RESEND] Fast TSC calibration fails with v3.14-rc1 and later

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Date:	Wed, 12 Mar 2014 17:20:02 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	joeyli <jlee@...e.com>
cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Julian Wollrath <jwollrath@....de>, x86@...nel.org,
	LKML <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [RESEND] Fast TSC calibration fails with v3.14-rc1 and later

On Wed, 12 Mar 2014, joeyli wrote:
> I think maybe still using ACPI_FADT_NO_CMOS_RTC to check does
> acpi_early_init() need run before timekeeping_init().
> If there have any future machine that applied ACPI TAD but "Fast TSC
> calibration" fail, at least the alternate TSC calibration can work
> around issue.

Well, it can work around, but it sucks as it's way slower than the
fast one. And we really don't want to pay that price for some half
baken ACPI nonsense.

Why exactly do you need that ACPI stuff before timekeeping_init()?

Thanks,

	tglx
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