From: Sean Mooney <smooney@redhat.com>
To: Cornelia Huck <cohuck@redhat.com>, Yan Zhao <yan.y.zhao@intel.com>
Cc: "Alex Williamson" <alex.williamson@redhat.com>,
"Daniel P.Berrangé" <berrange@redhat.com>,
kvm@vger.kernel.org, libvir-list@redhat.com,
"Jason Wang" <jasowang@redhat.com>,
qemu-devel@nongnu.org, kwankhede@nvidia.com, eauger@redhat.com,
xin-ran.wang@intel.com, corbet@lwn.net,
openstack-discuss@lists.openstack.org, shaohe.feng@intel.com,
kevin.tian@intel.com, "Parav Pandit" <parav@mellanox.com>,
jian-feng.ding@intel.com, dgilbert@redhat.com,
zhenyuw@linux.intel.com, hejie.xu@intel.com,
bao.yumeng@zte.com.cn, intel-gvt-dev@lists.freedesktop.org,
eskultet@redhat.com, "Jiri Pirko" <jiri@mellanox.com>,
dinechin@redhat.com, devel@ovirt.org
Subject: Re: device compatibility interface for live migration with assigned devices
Date: Thu, 10 Sep 2020 13:50:11 +0100 [thread overview]
Message-ID: <7cebcb6c8d1a1452b43e8358ee6ee18a150a0238.camel@redhat.com> (raw)
In-Reply-To: <20200910143822.2071eca4.cohuck@redhat.com>
On Thu, 2020-09-10 at 14:38 +0200, Cornelia Huck wrote:
> On Wed, 9 Sep 2020 10:13:09 +0800
> Yan Zhao <yan.y.zhao@intel.com> wrote:
>
> > > > still, I'd like to put it more explicitly to make ensure it's not missed:
> > > > the reason we want to specify compatible_type as a trait and check
> > > > whether target compatible_type is the superset of source
> > > > compatible_type is for the consideration of backward compatibility.
> > > > e.g.
> > > > an old generation device may have a mdev type xxx-v4-yyy, while a newer
> > > > generation device may be of mdev type xxx-v5-yyy.
> > > > with the compatible_type traits, the old generation device is still
> > > > able to be regarded as compatible to newer generation device even their
> > > > mdev types are not equal.
> > >
> > > If you want to support migration from v4 to v5, can't the (presumably
> > > newer) driver that supports v5 simply register the v4 type as well, so
> > > that the mdev can be created as v4? (Just like QEMU versioned machine
> > > types work.)
> >
> > yes, it should work in some conditions.
> > but it may not be that good in some cases when v5 and v4 in the name string
> > of mdev type identify hardware generation (e.g. v4 for gen8, and v5 for
> > gen9)
> >
> > e.g.
> > (1). when src mdev type is v4 and target mdev type is v5 as
> > software does not support it initially, and v4 and v5 identify hardware
> > differences.
>
> My first hunch here is: Don't introduce types that may be compatible
> later. Either make them compatible, or make them distinct by design,
> and possibly add a different, compatible type later.
>
> > then after software upgrade, v5 is now compatible to v4, should the
> > software now downgrade mdev type from v5 to v4?
> > not sure if moving hardware generation info into a separate attribute
> > from mdev type name is better. e.g. remove v4, v5 in mdev type, while use
> > compatible_pci_ids to identify compatibility.
>
> If the generations are compatible, don't mention it in the mdev type.
> If they aren't, use distinct types, so that management software doesn't
> have to guess. At least that would be my naive approach here.
yep that is what i would prefer to see too.
>
> >
> > (2) name string of mdev type is composed by "driver_name + type_name".
> > in some devices, e.g. qat, different generations of devices are binding to
> > drivers of different names, e.g. "qat-v4", "qat-v5".
> > then though type_name is equal, mdev type is not equal. e.g.
> > "qat-v4-type1", "qat-v5-type1".
>
> I guess that shows a shortcoming of that "driver_name + type_name"
> approach? Or maybe I'm just confused.
yes i really dont like haveing the version in the mdev-type name
i would stongly perfger just qat-type-1 wehere qat is just there as a way of namespacing.
although symmetric-cryto, asymmetric-cryto and compression woudl be a better name then type-1, type-2, type-3 if
that is what they would end up mapping too. e.g. qat-compression or qat-aes is a much better name then type-1
higher layers of software are unlikely to parse the mdev names but as a human looking at them its much eaiser to
understand if the names are meaningful. the qat prefix i think is important however to make sure that your mdev-types
dont colide with other vendeors mdev types. so i woudl encurage all vendors to prefix there mdev types with etiher the
device name or the vendor.
>
next prev parent reply other threads:[~2020-09-10 21:53 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-13 23:29 device compatibility interface for live migration with assigned devices Yan Zhao
2020-07-14 10:21 ` Daniel P. Berrangé
2020-07-14 12:33 ` Sean Mooney
[not found] ` <20200714110148.0471c03c@x1.home>
[not found] ` <eb705c72cdc8b6b8959b6ebaeeac6069a718d524.camel@redhat.com>
2020-07-14 21:15 ` Sean Mooney
2020-07-14 16:16 ` Alex Williamson
2020-07-14 16:47 ` Daniel P. Berrangé
2020-07-14 20:47 ` Alex Williamson
2020-07-15 9:16 ` Daniel P. Berrangé
2020-07-14 17:19 ` Dr. David Alan Gilbert
2020-07-14 20:59 ` Alex Williamson
2020-07-15 8:20 ` Yan Zhao
2020-07-15 8:49 ` Feng, Shaohe
2020-07-17 14:59 ` Alex Williamson
2020-07-17 18:03 ` Dr. David Alan Gilbert
2020-07-17 18:30 ` Alex Williamson
2020-07-15 8:23 ` Dr. David Alan Gilbert
[not found] ` <CAH7mGatPWsczh_rbVhx4a+psJXvkZgKou3r5HrEQTqE7SqZkKA@mail.gmail.com>
2020-07-17 15:18 ` Alex Williamson
2020-07-16 4:16 ` Jason Wang
2020-07-16 8:32 ` Yan Zhao
2020-07-16 9:30 ` Jason Wang
2020-07-17 16:12 ` Alex Williamson
2020-07-20 3:41 ` Jason Wang
2020-07-20 10:39 ` Sean Mooney
2020-07-21 2:11 ` Jason Wang
2020-07-21 0:51 ` Yan Zhao
2020-07-27 7:24 ` Yan Zhao
2020-07-27 22:23 ` Alex Williamson
2020-07-29 8:05 ` Yan Zhao
2020-07-29 11:28 ` Sean Mooney
2020-07-29 19:12 ` Alex Williamson
2020-07-30 3:41 ` Yan Zhao
2020-07-30 13:24 ` Sean Mooney
2020-07-30 17:29 ` Alex Williamson
2020-08-04 8:37 ` Yan Zhao
2020-08-05 9:44 ` Dr. David Alan Gilbert
2020-07-30 1:56 ` Yan Zhao
2020-07-30 13:14 ` Sean Mooney
2020-08-04 16:35 ` Cornelia Huck
2020-08-05 2:22 ` Jason Wang
2020-08-05 2:16 ` Yan Zhao
2020-08-05 2:41 ` Jason Wang
2020-08-05 7:56 ` Jiri Pirko
2020-08-05 8:02 ` Jason Wang
2020-08-05 9:33 ` Yan Zhao
2020-08-05 10:53 ` Jiri Pirko
2020-08-05 11:35 ` Sean Mooney
2020-08-07 11:59 ` Cornelia Huck
2020-08-13 15:33 ` Cornelia Huck
2020-08-13 19:02 ` Eric Farman
2020-08-17 6:38 ` Cornelia Huck
2020-08-10 7:46 ` Yan Zhao
2020-08-13 4:24 ` Jason Wang
2020-08-14 5:16 ` Yan Zhao
2020-08-14 12:30 ` Sean Mooney
2020-08-17 1:52 ` Yan Zhao
2020-08-18 3:24 ` Jason Wang
2020-08-18 8:55 ` Daniel P. Berrangé
2020-08-18 9:06 ` Cornelia Huck
2020-08-18 9:24 ` Daniel P. Berrangé
2020-08-18 9:38 ` Cornelia Huck
[not found] ` <3a073222-dcfe-c02d-198b-29f6a507b2e1@redhat.com>
2020-08-18 9:16 ` Daniel P. Berrangé
2020-08-18 9:36 ` Cornelia Huck
2020-08-18 9:39 ` Parav Pandit
2020-08-19 3:30 ` Yan Zhao
2020-08-19 5:58 ` Parav Pandit
2020-08-19 9:41 ` Jason Wang
2020-08-19 6:57 ` [ovirt-devel] " Jason Wang
2020-08-19 6:59 ` Yan Zhao
2020-08-19 7:39 ` Jason Wang
2020-08-19 8:13 ` Yan Zhao
2020-08-19 9:28 ` Jason Wang
2020-08-20 12:27 ` Cornelia Huck
2020-08-21 3:14 ` Jason Wang
2020-08-21 14:52 ` Cornelia Huck
2020-08-31 3:07 ` Jason Wang
2020-08-19 17:50 ` Alex Williamson
2020-08-20 0:18 ` Yan Zhao
2020-08-20 3:13 ` Alex Williamson
2020-08-20 3:09 ` Yan Zhao
2020-08-19 2:54 ` Jason Wang
2020-08-20 0:39 ` Yan Zhao
2020-08-20 1:29 ` Sean Mooney
2020-08-20 4:01 ` Yan Zhao
2020-08-20 5:16 ` Sean Mooney
2020-08-20 6:27 ` Yan Zhao
2020-08-20 13:24 ` Sean Mooney
2020-08-26 8:54 ` Yan Zhao
2020-08-20 3:22 ` Alex Williamson
2020-08-20 3:16 ` Yan Zhao
2020-08-25 14:39 ` Cornelia Huck
2020-08-26 6:41 ` Yan Zhao
2020-08-28 13:47 ` Cornelia Huck
2020-08-28 14:04 ` Sean Mooney
2020-08-31 4:43 ` Yan Zhao
2020-09-08 14:41 ` Cornelia Huck
2020-09-09 2:13 ` Yan Zhao
2020-09-10 12:38 ` Cornelia Huck
2020-09-10 12:50 ` Sean Mooney [this message]
2020-09-10 18:02 ` Alex Williamson
2020-09-11 0:56 ` Yan Zhao
2020-09-11 10:08 ` Cornelia Huck
2020-09-11 10:18 ` Tian, Kevin
2020-09-11 16:51 ` Alex Williamson
2020-09-14 13:48 ` Zeng, Xin
2020-09-14 14:44 ` Alex Williamson
2020-09-09 5:37 ` Yan Zhao
2020-08-31 2:23 ` Yan Zhao
2020-08-19 2:38 ` Jason Wang
2020-08-18 9:32 ` Parav Pandit
2020-08-19 2:45 ` Jason Wang
2020-08-19 5:26 ` Parav Pandit
2020-08-19 6:48 ` Jason Wang
2020-08-19 6:53 ` Parav Pandit
2020-07-29 19:05 ` Dr. David Alan Gilbert
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