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From: Christian Borntraeger <borntraeger@de.ibm.com>
To: David Hildenbrand <david@redhat.com>, qemu-devel@nongnu.org
Cc: Thomas Huth <thuth@redhat.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Richard Henderson <richard.henderson@linaro.org>,
	Halil Pasic <pasic@linux.ibm.com>,
	qemu-s390x@nongnu.org
Subject: Re: [PATCH v2 2/2] s390x/cpumodel: Introduce dynamic feature groups
Date: Tue, 26 Nov 2019 08:54:40 +0100	[thread overview]
Message-ID: <b062f580-d664-f68c-2364-1f65df6ee265@de.ibm.com> (raw)
In-Reply-To: <20191125172031.16282-3-david@redhat.com>



On 25.11.19 18:20, David Hildenbrand wrote:
> 
> As soon as dynamic feature groups are used, the CPU model becomes
> migration-unsafe. Upper layers can expand these models to migration-safe
> and static variants, allowing them to be migrated.

I really dislike that. I am trying to get rid of the unsafe variants (e.g. now
defaulting to host-model instead of host-passthrough). I do not want to give
users new ways of hurting themselves.

Unless I misunderstood Eduardo, I think his versioning approach is actually better
in regard to migration, no?
I z terms, you can still say -cpu z13  which is just an alias to z13v1 z13v2 etc.
Assuming that the version is checked this will be safe.



  reply	other threads:[~2019-11-26  7:55 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-25 17:20 [PATCH v2 0/2] s390x/cpumodel: Introduce dynamic feature group David Hildenbrand
2019-11-25 17:20 ` [PATCH v2 1/2] s390x/cpumodel: Factor out CPU feature dependencies David Hildenbrand
2019-11-25 17:20 ` [PATCH v2 2/2] s390x/cpumodel: Introduce dynamic feature groups David Hildenbrand
2019-11-26  7:54   ` Christian Borntraeger [this message]
2019-11-26  8:04     ` David Hildenbrand
2019-11-26 12:59       ` Christian Borntraeger
2019-11-26 14:07         ` David Hildenbrand
2019-11-29 19:33           ` Eduardo Habkost
2019-12-02  9:15             ` David Hildenbrand
2019-12-05 14:35               ` Eduardo Habkost
2019-12-05 14:48                 ` David Hildenbrand
2019-12-09 23:29                   ` Eduardo Habkost
2019-12-12 15:27                     ` David Hildenbrand
2019-11-25 23:20 ` [PATCH v2 0/2] s390x/cpumodel: Introduce dynamic feature group no-reply

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