Discussion of the VIRTIO specification
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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Parav Pandit <parav@nvidia.com>
Cc: Eugenio Perez Martin <eperezma@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	"virtio-comment@lists.oasis-open.org"
	<virtio-comment@lists.oasis-open.org>,
	"hengqi@linux.alibaba.com" <hengqi@linux.alibaba.com>,
	"xuanzhuo@linux.alibaba.com" <xuanzhuo@linux.alibaba.com>,
	Shahaf Shuler <shahafs@nvidia.com>
Subject: Re: [virtio-comment] RE: [PATCH v3 2/2] content: Support enabling virtqueue after DRIVER_OK stage
Date: Thu, 26 Oct 2023 05:26:24 -0400	[thread overview]
Message-ID: <20231026052317-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <PH0PR12MB5481692710B92E5C01A61D4CDCDDA@PH0PR12MB5481.namprd12.prod.outlook.com>

On Thu, Oct 26, 2023 at 09:22:25AM +0000, Parav Pandit wrote:
> 
> > From: Michael S. Tsirkin <mst@redhat.com>
> > Sent: Thursday, October 26, 2023 2:48 PM
> > 
> > On Thu, Oct 26, 2023 at 08:38:51AM +0000, Parav Pandit wrote:
> > > > 2 can be solved if we allow resetting a queue before DRIVER_OK,
> > > This is just the hack of enabling and reset for no apparent gain.
> > > Future devices may have many queues and enabling 1000 queues, resetting
> > them is just an ugly interface.
> > 
> > Yes I can't say I love it either. The main driver is to try and make it possible for
> > device to know in advance the max # of queues that will be used. We could
> > alternatively just add this in a config register maybe?
> 
> I didn't follow your suggestion - what you want to add in the config register?

The reason devices want vqs to be enabled before DRIVER_OK is so that
they can preallocate device resources. Problems with this:
- no way to fail
- wasting driver resources too

Idea: a new writeable common config space register max_vqs +
a way for device to fail. Maybe set it before FEATURES_OK?

-- 
MST


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  reply	other threads:[~2023-10-26  9:26 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-02  5:15 [virtio-comment] [PATCH v3 0/2] Support enabling virtqueue after DRIVER_OK Parav Pandit
2023-10-02  5:16 ` [virtio-comment] [PATCH v3 1/2] conformance: Add missing virtqueue reset conformance references Parav Pandit
2023-10-05 16:53   ` Eugenio Perez Martin
2023-10-02  5:16 ` [virtio-comment] [PATCH v3 2/2] content: Support enabling virtqueue after DRIVER_OK stage Parav Pandit
2023-10-05 16:53   ` Eugenio Perez Martin
2023-10-12  6:39   ` [virtio-comment] " Xuan Zhuo
2023-10-17 12:25   ` Cornelia Huck
2023-10-17 12:48     ` [virtio-comment] " Parav Pandit
2023-10-18 10:25       ` Cornelia Huck
2023-10-18 10:28         ` Michael S. Tsirkin
2023-10-18 11:03           ` Cornelia Huck
2023-10-18 11:12             ` Michael S. Tsirkin
2023-10-18 11:12             ` Parav Pandit
2023-10-19 13:57               ` Parav Pandit
2023-10-23 13:29                 ` Parav Pandit
2023-10-23 13:57                   ` Cornelia Huck
2023-10-23 14:00                     ` Parav Pandit
2023-10-23 14:27                       ` Cornelia Huck
2023-10-23 14:53                         ` Parav Pandit
2023-10-23 15:01                           ` Cornelia Huck
2023-10-23 15:21                             ` Parav Pandit
2023-10-25  9:55                               ` Parav Pandit
2023-10-25 10:18                                 ` Cornelia Huck
2023-10-25 10:20                                   ` Parav Pandit
2023-10-25 10:24                                 ` Michael S. Tsirkin
2023-10-26  3:30                                   ` Parav Pandit
2023-10-26  5:39                                     ` Michael S. Tsirkin
2023-10-26  6:02                                       ` Parav Pandit
2023-10-26  6:24                                         ` Michael S. Tsirkin
2023-10-26  6:47                                           ` Parav Pandit
2023-10-26  8:27                                         ` Eugenio Perez Martin
2023-10-26  8:38                                           ` Parav Pandit
2023-10-26  9:15                                             ` Michael S. Tsirkin
2023-10-26  9:24                                               ` Parav Pandit
2023-10-26  9:27                                                 ` Michael S. Tsirkin
2023-10-26  9:45                                                   ` Parav Pandit
2023-10-27 10:13                                                     ` Cornelia Huck
2023-10-27 10:28                                                       ` Parav Pandit
2023-10-27 11:46                                                         ` Cornelia Huck
2023-10-27 11:55                                                           ` Parav Pandit
2023-10-26  9:18                                             ` Michael S. Tsirkin
2023-10-26  9:22                                               ` Parav Pandit
2023-10-26  9:26                                                 ` Michael S. Tsirkin [this message]
2023-10-02  5:20 ` [virtio-comment] RE: [PATCH v3 0/2] Support enabling virtqueue after DRIVER_OK Parav Pandit
2023-10-10  4:57   ` Parav Pandit
2023-10-16 16:30     ` Parav Pandit
2023-10-17 11:58       ` Cornelia Huck
2023-10-17 12:50         ` Parav Pandit

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