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From: Alexey Kardashevskiy <aik@ozlabs.ru>
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Date: Sun, 6 Sep 2015 16:14:25 +1000
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Subject: Re: [Qemu-devel] [PATCH qemu] spapr: Enable in-kernel H_SET_MODE
	handling
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To: David Gibson <david@gibson.dropbear.id.au>
Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org

On 09/04/2015 02:48 PM, David Gibson wrote:
> On Wed, Sep 02, 2015 at 07:29:58PM +1000, Alexey Kardashevskiy wrote:
>> For setting debug watchpoints, sPAPR guests use H_SET_MODE hypercall.
>> The existing QEMU H_SET_MODE handler does not support this but
>> the KVM handler in HV KVM does. However it is not enabled.
>>
>> This enables the in-kernel H_SET_MODE handler which handles:
>> - Completed Instruction Address Breakpoint Register
>> - Watch point 0 registers.
>>
>> The rest is still handled in QEMU.
>>
>> Reported-by: Anton Blanchard <anton@samba.org>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>
> Applied to spapr-dev; I'll move it into spapr-next once it's had a
> little more testing.

Another thing to keep in mind is that at some point in the past the host 
kernel used to handle H_SET_MODE and QEMU did not have the handler at all, 
now this functionality is in QEMU but some RHEL kernel could have picked a 
kernel with the in-kernel handler.


-- 
Alexey