From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <dev-bounces@dpdk.org>
Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124])
	by inbox.dpdk.org (Postfix) with ESMTP id 9320941CE5;
	Mon, 20 Feb 2023 10:43:24 +0100 (CET)
Received: from mails.dpdk.org (localhost [127.0.0.1])
	by mails.dpdk.org (Postfix) with ESMTP id 7D08A42FBA;
	Mon, 20 Feb 2023 10:43:24 +0100 (CET)
Received: from smartserver.smartsharesystems.com
 (smartserver.smartsharesystems.com [77.243.40.215])
 by mails.dpdk.org (Postfix) with ESMTP id 8BA5E40395
 for <dev@dpdk.org>; Mon, 20 Feb 2023 10:43:23 +0100 (CET)
X-MimeOLE: Produced By Microsoft Exchange V6.5
Content-class: urn:content-classes:message
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Subject: RE: [PATCH] net/hns3: support disable IOVA as PA mode
Date: Mon, 20 Feb 2023 10:43:17 +0100
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35D87754@smartserver.smartshare.dk>
In-Reply-To: <7487991.nlapOpYt14@thomas>
X-MS-Has-Attach: 
X-MS-TNEF-Correlator: 
Thread-Topic: [PATCH] net/hns3: support disable IOVA as PA mode
Thread-Index: AdlE/z7LS08JuJCESgmnt9vdFRiRVQADARgQ
References: <20230214071141.50155-1-fengchengwen@huawei.com>
 <AS8PR08MB708060E6F7DC9D086D4C1C379EA09@AS8PR08MB7080.eurprd08.prod.outlook.com>
 <7487991.nlapOpYt14@thomas>
From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: "Thomas Monjalon" <thomas@monjalon.net>, <bruce.richardson@intel.com>,
 "Chengwen Feng" <fengchengwen@huawei.com>,
 "Ruifeng Wang" <Ruifeng.Wang@arm.com>
Cc: <dev@dpdk.org>, "nd" <nd@arm.com>, <ferruh.yigit@amd.com>,
 "Dongdong Liu" <liudongdong3@huawei.com>,
 "Yisen Zhuang" <yisen.zhuang@huawei.com>
X-BeenThere: dev@dpdk.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: DPDK patches and discussions <dev.dpdk.org>
List-Unsubscribe: <https://mails.dpdk.org/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://mails.dpdk.org/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <https://mails.dpdk.org/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org

> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> Sent: Monday, 20 February 2023 08.45
>=20
> 16/02/2023 09:36, Ruifeng Wang:
> > From: Chengwen Feng <fengchengwen@huawei.com>
> > > Subject: [PATCH] net/hns3: support disable IOVA as PA mode
>=20
> Could we change the title to "support IOVA as VA" ?

The underlying problem is the meson configuration option name for this =
feature [1]:

option('enable_iova_as_pa', type: 'boolean', value: true, description:
       'Support for IOVA as physical address. Disabling removes the =
buf_iova field of mbuf.')

[1]: =
https://elixir.bootlin.com/dpdk/v22.11.1/source/meson_options.txt#L43

Formally, the patch provides the ability to set a boolean configuration =
value ("enable_iova_as_pa") to false, and thus the patch title is =
correct.

Nonetheless, I agree that the title suggested by Thomas is an =
improvement.


Going back to the root cause, I think the configuration option should be =
an enum instead of a boolean, e.g. "iova_mode" with values "iova_pa" and =
"iova_va".

It's somewhat similar to CPU endian macros. We have macros defining both =
Big Endian and Little Endian, not just one macro defining Big Endian or =
not.

@Bruce, would it be hard for you to change the IOVA configuration option =
from a boolean to a two-value enum?

Or - also considering the resulting #define's - would it be too =
difficult to keep a sufficient level of backwards/API compatibility?