[PATCH v2] Drivers: HV: Send one page worth of kmsg dump over Hyper-V during panic

[Greg KH]

On Fri, May 18, 2018 at 07:09:10PM +0000, Sunil Muthuswamy wrote:
> In the VM mode on Hyper-V, currently, when the kernel panics, an error
> code and few register values are populated in an MSR and the Hypervisor
> notified. This information is collected on the host. The amount of
> information currently collected is found to be limited and not very
> actionable. To gather more actionable data, such as stack trace, the
> proposal is to write one page worth of kmsg data on an allocated page
> and the Hypervisor notified of the page address through the MSR.
> 
> - Added a sysctl option to control the behavior, with ON by default.
> 
> CC: kys at microsoft.com
> CC: sthemmin at microsoft.com
> Signed-off-by: Sunil Muthuswamy <sunilmut at microsoft.com>
> ---
>  arch/x86/hyperv/hv_init.c          |  35 ++++++++++
>  arch/x86/include/asm/hyperv-tlfs.h |   5 +-
>  arch/x86/include/asm/mshyperv.h    |   1 +
>  drivers/hv/vmbus_drv.c             | 128 +++++++++++++++++++++++++++++++++++++
>  4 files changed, 167 insertions(+), 2 deletions(-)

What changed from v1?  Always put that below the --- line as the
documentation says to.

thanks,

greg k-h