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From: Stephen Hemminger <stephen@networkplumber.org>
To: Olivier Matz <olivier.matz@6wind.com>
Cc: Thomas Monjalon <thomas@monjalon.net>,
	Shijith Thotton <sthotton@marvell.com>,
	dev@dpdk.org, pbhagavatula@marvell.com,
	Honnappa.Nagarahalli@arm.com, bruce.richardson@intel.com,
	jerinj@marvell.com, mb@smartsharesystems.com,
	david.marchand@redhat.com
Subject: Re: [PATCH v3 2/5] mbuf: add second dynamic field member for VA only build
Date: Wed, 28 Sep 2022 12:48:27 -0700	[thread overview]
Message-ID: <20220928124827.790ba22f@hermes.local> (raw)
In-Reply-To: <YzRDn0DNSOunIuYV@platinum>

On Wed, 28 Sep 2022 14:52:47 +0200
Olivier Matz <olivier.matz@6wind.com> wrote:

> On Wed, Sep 28, 2022 at 09:24:51AM +0200, Thomas Monjalon wrote:
> > 21/09/2022 15:56, Shijith Thotton:  
> > > mbuf physical address field is not used in builds which only uses VA. It
> > > is used to expand the dynamic field area.
> > > 
> > > Signed-off-by: Shijith Thotton <sthotton@marvell.com>  
> > 
> > We cannot condition the use of the dynamic field.
> > I think it is enough justification to reject this patch.  
> 
> I don't think it is an issue.
> 
> > And about adding a compilation option for IOVA in the first patch of this series,
> > I think it is not the direction the majority wants DPDK to go.
> > We tend to avoid compilation options.  
> 
> In general, I agree that we don't want to have many custom compile-time options,
> especially if they impact ABI. It has several issues that have already been
> widely discussed.
> 
> However, in this specific case, we can suppose that removing buf_iova is a
> long-term goal (in years). Having this compile-time option is a way to test this
> approach, and progressively prepare the drivers to support it. Then, in few
> years (if we are still convinced), we may announce an abi breakage and switch to
> this new mode by default.

Since field is invalid if compile option is set,
shouldn't the field be inside an #ifdef so that if a driver or application
was to make the mistake of using that directly, it would fail at compile
time instead of runtime.

Leaving booby traps for applications and drivers is bad design.

  parent reply	other threads:[~2022-09-28 19:48 UTC|newest]

Thread overview: 88+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-30 16:25 [PATCH] mbuf: add mbuf physical address field to dynamic field Shijith Thotton
2022-06-30 16:45 ` Stephen Hemminger
2022-07-01 12:16   ` Shijith Thotton
2022-07-01 12:24   ` Shijith Thotton
2022-07-03  7:31     ` Morten Brørup
2022-07-04 14:00       ` Bruce Richardson
2022-08-03 15:34         ` [EXT] " Shijith Thotton
2022-08-29 15:16           ` [PATCH v1 0/4] mbuf dynamic field expansion Shijith Thotton
2022-09-07 13:43             ` [PATCH v2 0/5] " Shijith Thotton
2022-09-21  9:43               ` David Marchand
2022-09-21 14:01                 ` [EXT] " Shijith Thotton
2022-09-21 13:56               ` [PATCH v3 " Shijith Thotton
2022-09-21 13:56                 ` [PATCH v3 1/5] build: add meson option to configure IOVA mode as VA Shijith Thotton
2022-09-28 12:52                   ` Olivier Matz
2022-09-29  5:48                     ` [EXT] " Shijith Thotton
2022-09-21 13:56                 ` [PATCH v3 2/5] mbuf: add second dynamic field member for VA only build Shijith Thotton
2022-09-28  7:24                   ` Thomas Monjalon
2022-09-28 12:52                     ` Olivier Matz
2022-09-28 19:33                       ` Thomas Monjalon
2022-09-28 19:48                       ` Stephen Hemminger [this message]
2022-09-29  6:13                         ` [EXT] " Shijith Thotton
2022-09-28 12:52                   ` Olivier Matz
2022-09-21 13:56                 ` [PATCH v3 3/5] lib: move mbuf next pointer to first cache line Shijith Thotton
2022-09-21 14:07                   ` Morten Brørup
2022-09-28 12:52                   ` Olivier Matz
2022-09-29  6:14                     ` [EXT] " Shijith Thotton
2022-09-21 13:56                 ` [PATCH v3 4/5] drivers: mark Marvell cnxk PMDs work with IOVA as VA Shijith Thotton
2022-09-28 12:53                   ` Olivier Matz
2022-09-29  6:19                     ` [EXT] " Shijith Thotton
2022-09-29  7:44                       ` Olivier Matz
2022-09-29  8:10                         ` Shijith Thotton
2022-10-07 20:17                   ` Olivier Matz
2022-10-07 20:22                     ` [EXT] " Shijith Thotton
2022-09-21 13:56                 ` [PATCH v3 5/5] drivers: mark software " Shijith Thotton
2022-09-28  5:41                 ` [PATCH v3 0/5] mbuf dynamic field expansion Shijith Thotton
2022-09-28 12:52                 ` Olivier Matz
2022-09-29  4:51                   ` [EXT] " Shijith Thotton
2022-10-07 13:50                 ` Thomas Monjalon
2022-10-07 19:35                   ` [EXT] " Shijith Thotton
2022-10-07 19:30                 ` [PATCH v4 0/7] " Shijith Thotton
2022-10-07 19:30                   ` [PATCH v4 1/7] mbuf: add API to get and set mbuf physical address Shijith Thotton
2022-10-07 20:16                     ` Olivier Matz
2022-10-07 20:20                       ` [EXT] " Shijith Thotton
2022-10-07 19:30                   ` [PATCH v4 2/7] test/dma: use API to get mbuf data " Shijith Thotton
2022-10-07 20:17                     ` Olivier Matz
2022-10-07 19:30                   ` [PATCH v4 3/7] build: add meson option to configure IOVA mode as PA Shijith Thotton
2022-10-07 19:30                   ` [PATCH v4 4/7] mbuf: add second dynamic field member Shijith Thotton
2022-10-07 19:30                   ` [PATCH v4 5/7] lib: move mbuf next pointer to first cache line Shijith Thotton
2022-10-07 19:30                   ` [PATCH v4 6/7] drivers: mark cnxk PMDs work with IOVA as PA disabled Shijith Thotton
2022-10-07 19:30                   ` [PATCH v4 7/7] drivers: mark software " Shijith Thotton
2022-10-07 20:19                   ` [PATCH v4 0/7] mbuf dynamic field expansion Olivier Matz
2022-10-07 21:02                   ` [PATCH v5 " Shijith Thotton
2022-10-07 21:02                     ` [PATCH v5 1/7] mbuf: add API to get and set mbuf physical address Shijith Thotton
2022-10-07 21:20                       ` Stephen Hemminger
2022-10-07 21:02                     ` [PATCH v5 2/7] test/dma: use API to get mbuf data " Shijith Thotton
2022-10-07 21:02                     ` [PATCH v5 3/7] build: add meson option to configure IOVA mode as PA Shijith Thotton
2022-10-07 21:02                     ` [PATCH v5 4/7] mbuf: add second dynamic field member Shijith Thotton
2022-10-07 21:02                     ` [PATCH v5 5/7] lib: move mbuf next pointer to first cache line Shijith Thotton
2022-10-07 21:22                       ` Stephen Hemminger
2022-10-07 21:30                         ` [EXT] " Shijith Thotton
2022-10-07 21:02                     ` [PATCH v5 6/7] drivers: mark cnxk PMDs work with IOVA as PA disabled Shijith Thotton
2022-10-07 21:02                     ` [PATCH v5 7/7] drivers: mark software " Shijith Thotton
2022-10-09  9:34                     ` [PATCH v5 0/7] mbuf dynamic field expansion Thomas Monjalon
2022-09-07 13:43             ` [PATCH v2 1/5] build: add meson option to configure IOVA mode as VA Shijith Thotton
2022-09-07 15:31               ` Stephen Hemminger
2022-09-07 15:38                 ` Bruce Richardson
2022-09-07 21:33                   ` Morten Brørup
2022-09-07 13:43             ` [PATCH v2 2/5] mbuf: add second dynamic field member for VA only build Shijith Thotton
2022-09-07 13:43             ` [PATCH v2 3/5] lib: move mbuf next pointer to first cache line Shijith Thotton
2022-09-07 13:43             ` [PATCH v2 4/5] drivers: mark Marvell cnxk PMDs work with IOVA as VA Shijith Thotton
2022-09-07 13:43             ` [PATCH v2 5/5] drivers: mark software " Shijith Thotton
2022-08-29 15:16           ` [PATCH v1 1/4] build: add meson option to configure IOVA mode " Shijith Thotton
2022-08-29 18:18             ` Morten Brørup
2022-08-30  8:32               ` Bruce Richardson
2022-08-29 15:16           ` [PATCH v1 2/4] mbuf: add second dynamic field member for VA only build Shijith Thotton
2022-08-29 18:32             ` Morten Brørup
2022-08-30  8:35               ` Bruce Richardson
2022-08-30  8:41                 ` [EXT] " Pavan Nikhilesh Bhagavatula
2022-08-30 13:22                   ` Honnappa Nagarahalli
2022-09-07 13:55                     ` Shijith Thotton
2022-08-29 15:16           ` [PATCH v1 3/4] drivers: mark Marvell cnxk PMDs work with IOVA as VA Shijith Thotton
2022-08-29 15:16           ` [PATCH v1 4/4] drivers: mark software " Shijith Thotton
2022-08-30 13:07     ` [PATCH] mbuf: add mbuf physical address field to dynamic field Ferruh Yigit
2022-09-12 13:19       ` [EXT] " Shijith Thotton
2022-06-30 16:55 ` Bruce Richardson
2022-07-01  9:48   ` Olivier Matz
2022-07-01 11:53     ` Slava Ovsiienko
2022-07-01 12:01     ` [EXT] " Shijith Thotton

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