Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Parav Pandit <parav@mellanox.com>
To:     Cornelia Huck <cohuck@redhat.com>,
        Alex Williamson <alex.williamson@redhat.com>
CC:     Jiri Pirko <jiri@mellanox.com>,
        "David S . Miller" <davem@davemloft.net>,
        Kirti Wankhede <kwankhede@nvidia.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        cjia <cjia@nvidia.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: RE: [PATCH v2 0/2] Simplify mtty driver and mdev core
Thread-Topic: [PATCH v2 0/2] Simplify mtty driver and mdev core
Thread-Index: AQHVTfNxjgfwJJG2ZUiuOAmKCwQvf6bx3uKAgAWJU4CAAcVCEIAABCsAgAAWVtCAABCDgIAAzoewgAAqE4CAAECFQIAAFWyAgAAGbNCAABfqAIAAErcwgAjpulCAAJkHAIAACiGAgACnvZA=
Date:   Wed, 21 Aug 2019 03:57:19 +0000
Message-ID: <AM0PR05MB48660532A1A063FF1BD5E4AED1AA0@AM0PR05MB4866.eurprd05.prod.outlook.com>
References: <20190802065905.45239-1-parav@mellanox.com>
        <20190808141255.45236-1-parav@mellanox.com>     <20190808170247.1fc2c4c4@x1.home>
        <77ffb1f8-e050-fdf5-e306-0a81614f7a88@nvidia.com>
        <AM0PR05MB4866993536C0C8ACEA2F92DBD1D20@AM0PR05MB4866.eurprd05.prod.outlook.com>
        <20190813085246.1d642ae5@x1.home>
        <AM0PR05MB48663579A340E6597B3D01BCD1D20@AM0PR05MB4866.eurprd05.prod.outlook.com>
        <20190813111149.027c6a3c@x1.home>
        <AM0PR05MB4866D40F8EBB382C78193C91D1AD0@AM0PR05MB4866.eurprd05.prod.outlook.com>
        <20190814100135.1f60aa42.cohuck@redhat.com>
        <AM0PR05MB4866ABFDDD9DDCBC01F6CA90D1AD0@AM0PR05MB4866.eurprd05.prod.outlook.com>
        <20190814150911.296da78c.cohuck@redhat.com>
        <AM0PR05MB48666CCDFE985A25F42A0259D1AD0@AM0PR05MB4866.eurprd05.prod.outlook.com>
        <20190814085746.26b5f2a3@x1.home>
        <AM0PR05MB4866148ABA3C4E48E73E95FCD1AD0@AM0PR05MB4866.eurprd05.prod.outlook.com>
        <AM0PR05MB48668B6221E477A873688CDBD1AB0@AM0PR05MB4866.eurprd05.prod.outlook.com>
        <20190820111904.75515f58@x1.home> <20190820195519.47d6fd6a.cohuck@redhat.com>
In-Reply-To: <20190820195519.47d6fd6a.cohuck@redhat.com>
Accept-Language: en-US
Content-Language: en-US
received-spf: None (protection.outlook.com: mellanox.com does not designate
 permitted sender hosts)
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: e0456287-cccd-4ab9-44d0-08d725ebaa0c
X-MS-Exchange-CrossTenant-originalarrivaltime: 21 Aug 2019 03:57:19.4308
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: a652971c-7d2e-4d9b-a6a4-d149256f461b
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: 6U/IJWC/BWzUbGPurpf/eNj6UVxYPo1OZjQ4UiLreNQnS9+/zdOYMghZeQN60PdjrbZOwBgqPtk68FMjwt0lTg==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM0PR05MB5089
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


> -----Original Message-----
> From: Cornelia Huck <cohuck@redhat.com>
> Sent: Tuesday, August 20, 2019 11:25 PM
> To: Alex Williamson <alex.williamson@redhat.com>
> Cc: Parav Pandit <parav@mellanox.com>; Jiri Pirko <jiri@mellanox.com>;
> David S . Miller <davem@davemloft.net>; Kirti Wankhede
> <kwankhede@nvidia.com>; kvm@vger.kernel.org; linux-
> kernel@vger.kernel.org; cjia <cjia@nvidia.com>; netdev@vger.kernel.org
> Subject: Re: [PATCH v2 0/2] Simplify mtty driver and mdev core
>=20
> On Tue, 20 Aug 2019 11:19:04 -0600
> Alex Williamson <alex.williamson@redhat.com> wrote:
>=20
> > What about an alias based on the uuid?  For example, we use 160-bit
> > sha1s daily with git (uuids are only 128-bit), but we generally don't
> > reference git commits with the full 20 character string.  Generally 12
> > characters is recommended to avoid ambiguity.  Could mdev
> > automatically create an abbreviated sha1 alias for the device?  If so,
> > how many characters should we use and what do we do on collision?  The
> > colliding device could add enough alias characters to disambiguate (we
> > likely couldn't re-alias the existing device to disambiguate, but I'm
> > not sure it matters, userspace has sysfs to associate aliases).  Ex.
> >
> > UUID=3D$(uuidgen)
> > ALIAS=3D$(echo $UUID | sha1sum | colrm 13)
> >
> > Since there seems to be some prefix overhead, as I ask about above in
> > how many characters we actually have to work with in IFNAMESZ, maybe
> > we start with 8 characters (matching your "index" namespace) and
> > expand as necessary for disambiguation.  If we can eliminate overhead
> > in IFNAMESZ, let's start with 12.  Thanks,
> >
> > Alex
>=20
> I really like that idea, and it seems the best option proposed yet, as we=
 don't
> need to create a secondary identifier.
User setting this alias at mdev creation time and exposed via sysfs as read=
 only attribute works.
Exposing that as
const char *mdev_alias(struct mdev_device *dev) to vendor drivers..