linux-kernel - Re: tsc breaks atkbd suspend

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Message-ID: <20080219093738.GA1423@elf.ucw.cz>
Date:	Tue, 19 Feb 2008 10:37:38 +0100
From:	Pavel Machek <pavel@....cz>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	kernel list <linux-kernel@...r.kernel.org>, jikos@...e.cz,
	Ingo Molnar <mingo@...e.hu>, "Rafael J. Wysocki" <rjw@...k.pl>,
	Andrew Morton <akpm@...l.org>
Subject: Re: tsc breaks atkbd suspend

Hi!

This is wrong:

#ifdef CONFIG_X86_TSC
static int __init tsc_setup(char *str)
{
        printk(KERN_WARNING "notsc: Kernel compiled with
CONFIG_X86_TSC, "
                                "cannot disable TSC.\n");
        return 1;
}
#else
/*
 * disable flag for tsc. Takes effect by clearing the TSC cpu flag
 * in cpu/common.c
 */
static int __init tsc_setup(char *str)
{
        setup_clear_cpu_cap(X86_FEATURE_TSC);
        return 1;
}
#endif

...even if kernel is compiled with X86_TSC, we do disable it in case
it is unstable:

#if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86_TSC)
                /* TSC halts in C2, so notify users */
                if (tsc_halts_in_c(ACPI_STATE_C2))
                        mark_tsc_unstable("possible TSC halt in C2");
#endif

...so the commandline option should work, too.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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