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References: <20171207153141.15523-1-david@redhat.com>
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From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Fri, 8 Dec 2017 14:00:01 +0100
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Subject: Re: [Qemu-devel] [PATCH v2 for-2.12 4/5] s390x/tcg: indicate value
 of TODPR in STCKE
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To: David Hildenbrand <david@redhat.com>, Richard Henderson <rth@twiddle.net>, qemu-s390x@nongnu.org, qemu-devel@nongnu.org
Cc: Cornelia Huck <cohuck@redhat.com>, Alexander Graf <agraf@suse.de>



On 12/08/2017 01:45 PM, David Hildenbrand wrote:
> On 08.12.2017 01:02, Richard Henderson wrote:
>> On 12/07/2017 07:31 AM, David Hildenbrand wrote:
>>> +    /* 16 bit value store in an uint32_t (only valid bits set) */
>>> +    tcg_gen_ld32u_i64(todpr, cpu_env, offsetof(CPUS390XState, todpr));
>>
>> Any reason not to use a uint16_t and use tcg_gen_ld16u_i64 here?
>>
> 
> Yes, KVM introduced and uses this field. As it is used for migration, we
> cannot easily change it. (any maybe it was designed that way for future
> changes)

FWIW, if you look at the POP the TOD programmable register is 32bit (of which
bits 0-15 in IBM speak) are 0.