linux-kernel - RE: [PATCH 0/4] Introduce variable length mdev alias

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Date:   Tue, 27 Aug 2019 13:11:17 +0000
From:   Parav Pandit <parav@...lanox.com>
To:     Parav Pandit <parav@...lanox.com>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        Jiri Pirko <jiri@...lanox.com>,
        "kwankhede@...dia.com" <kwankhede@...dia.com>,
        "cohuck@...hat.com" <cohuck@...hat.com>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH 0/4] Introduce variable length mdev alias

Hi Alex, Cornelia,

> -----Original Message-----
> From: kvm-owner@...r.kernel.org <kvm-owner@...r.kernel.org> On Behalf
> Of Parav Pandit
> Sent: Tuesday, August 27, 2019 2:11 AM
> To: alex.williamson@...hat.com; Jiri Pirko <jiri@...lanox.com>;
> kwankhede@...dia.com; cohuck@...hat.com; davem@...emloft.net
> Cc: kvm@...r.kernel.org; linux-kernel@...r.kernel.org;
> netdev@...r.kernel.org; Parav Pandit <parav@...lanox.com>
> Subject: [PATCH 0/4] Introduce variable length mdev alias
> 
> To have consistent naming for the netdevice of a mdev and to have consistent
> naming of the devlink port [1] of a mdev, which is formed using
> phys_port_name of the devlink port, current UUID is not usable because UUID
> is too long.
> 
> UUID in string format is 36-characters long and in binary 128-bit.
> Both formats are not able to fit within 15 characters limit of netdev name.
> 
> It is desired to have mdev device naming consistent using UUID.
> So that widely used user space framework such as ovs [2] can make use of
> mdev representor in similar way as PCIe SR-IOV VF and PF representors.
> 
> Hence,
> (a) mdev alias is created which is derived using sha1 from the mdev name.
> (b) Vendor driver describes how long an alias should be for the child mdev
> created for a given parent.
> (c) Mdev aliases are unique at system level.
> (d) alias is created optionally whenever parent requested.
> This ensures that non networking mdev parents can function without alias
> creation overhead.
> 
> This design is discussed at [3].
> 
> An example systemd/udev extension will have,
> 
> 1. netdev name created using mdev alias available in sysfs.
> 
> mdev UUID=83b8f4f2-509f-382f-3c1e-e6bfe0fa1001
> mdev 12 character alias=cd5b146a80a5
> 
> netdev name of this mdev = enmcd5b146a80a5 Here en = Ethernet link m =
> mediated device
> 
> 2. devlink port phys_port_name created using mdev alias.
> devlink phys_port_name=pcd5b146a80a5
> 
> This patchset enables mdev core to maintain unique alias for a mdev.
> 
> Patch-1 Introduces mdev alias using sha1.
> Patch-2 Ensures that mdev alias is unique in a system.
> Patch-3 Exposes mdev alias in a sysfs hirerchy.
> Patch-4 Extends mtty driver to optionally provide alias generation.
> This also enables to test UUID based sha1 collision and trigger error handling
> for duplicate sha1 results.
> 
> In future when networking driver wants to use mdev alias, mdev_alias() API will
> be added to derive devlink port name.
> 
Now that majority of above patches looks in shape and I addressed all comments,
In next v1 post, I was considering to include mdev_alias() and have example use in mtty driver.

This way, subsequent series of mlx5_core who intents to use mdev_alias() API makes it easy to review and merge through Dave M, netdev tree.
Is that ok with you?