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    SubjectRe: [PATCH] x86: Hyper-V: register clocksource only if its advertised
    On Fri, Jan 25, 2013 at 02:37:16PM +0100, Olaf Hering wrote:
    > Enable hyperv_clocksource only if its advertised as a feature.
    > XenServer 6 returns the signature which is checked in
    > ms_hyperv_platform(), but it does not offer all features. Currently the
    > clocksource is enabled unconditionally in ms_hyperv_init_platform(), and
    > the result is a hanging guest.
    >
    > Hyper-V spec Bit 1 indicates the availability of Partition Reference
    > Counter. Register the clocksource only if this bit is set.
    >
    > The guest in question prints this in dmesg:
    > [ 0.000000] Hypervisor detected: Microsoft HyperV
    > [ 0.000000] HyperV: features 0x70, hints 0x0
    >
    > This bug can be reproduced easily be setting 'viridian=1' in a HVM domU
    > .cfg file. A workaround without this patch is to boot the HVM guest with
    > 'clocksource=jiffies'.
    >
    > Signed-off-by: Olaf Hering <olaf@aepfle.de>
    > Cc: stable@kernel.org
    > Cc: KY Srinivasan <kys@microsoft.com>
    > Cc: Greg KH <gregkh@linuxfoundation.org>
    > ---
    > arch/x86/kernel/cpu/mshyperv.c | 3 ++-
    > 1 file changed, 2 insertions(+), 1 deletion(-)

    This needs to go through the x86 maintainers, not me, sorry.

    greg k-h


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