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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>, Al Viro <viro@zeniv.linux.org.uk>,
	Adam Borowski <kilobyte@angband.pl>,
	Michal Marek <mmarek@suse.com>, Philip Muller <philm@manjaro.org>,
	linux-kernel@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	linux-arch <linux-arch@vger.kernel.org>,
	linux-kbuild <linux-kbuild@vger.kernel.org>
Subject: Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm
Date: Thu, 24 Nov 2016 08:36:39 +0100	[thread overview]
Message-ID: <20161124073639.GA12728@kroah.com> (raw)
In-Reply-To: <20161124182026.34e6570b@roar.ozlabs.ibm.com>

On Thu, Nov 24, 2016 at 06:20:26PM +1100, Nicholas Piggin wrote:
> But still, modversions is pretty complicated for what it gives us. It sends
> preprocessed C into a C parser that makes CRCs using type definitions of
> exported symbols, then turns those CRCs into a linker script which which is
> used to link the .o file with. What we get in return is a quite limited and
> symbol "versioning" system.
> 
> What if we ripped all that out and just attached an explicit version to
> each export, and incompatible changes require an increment?

How would that work for structures?  Would that be required for every
EXPORT_SYMBOL* somehow?

> Google tells me
> Linus is not a neutral bystander on the topic of symbol versioning, so I'm
> bracing for a robust response :) (actually I don't much care either way, I'm
> happy to put a couple of bandaids on it and keep it going)

There are tools that people are working on to make it more obvious where
API breaks happen by looking at the .o debug data instead of our crazy
current system (which is really better than nothing), perhaps we should
start using them instead?

See here for more details about this:
	https://kernel-recipes.org/en/2016/talks/would-an-abi-changes-visualization-tool-be-useful-to-linux-kernel-maintenance/

thanks,

greg k-h

  reply	other threads:[~2016-11-24  7:36 UTC|newest]

Thread overview: 113+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <a73aec83-ddad-2bdf-e612-178c9936a16f@manjaro.org>
     [not found] ` <20161102004639.6870806d@roar.ozlabs.ibm.com>
2016-11-23 20:08   ` BUG: 4.9-rc6 Still "no symbol version" on boot Philip Müller
2016-11-23 20:14     ` Robert LeBlanc
2016-11-23 20:27       ` Philip Müller
2016-11-23 20:53     ` Adam Borowski
2016-11-23 21:01       ` Robert LeBlanc
2016-11-23 21:02       ` [PATCH] x86/kbuild: enable modversions for symbols exported from asm Adam Borowski
2016-11-23 23:10         ` Philip Müller
2016-11-24  4:40         ` Ingo Molnar
2016-11-24  5:20           ` Nicholas Piggin
2016-11-24  6:00             ` Ingo Molnar
2016-11-24  7:20               ` Nicholas Piggin
2016-11-24  7:36                 ` Greg Kroah-Hartman [this message]
2016-11-24  7:53                   ` Nicholas Piggin
2016-11-24  9:32                     ` Michal Marek
2016-11-24 10:03                       ` Nicholas Piggin
2016-11-24 10:51                         ` Michal Marek
2016-11-24  9:38                     ` Arnd Bergmann
2016-11-24 10:01                       ` Nicholas Piggin
2016-11-24  9:56                     ` Greg Kroah-Hartman
2016-11-24 10:31                       ` Nicholas Piggin
2016-11-24 15:24                         ` Greg Kroah-Hartman
2016-11-25  0:40                           ` Nicholas Piggin
2016-11-25 18:00                             ` Linus Torvalds
2016-11-26  0:37                               ` Nicholas Piggin
2016-11-29  1:15                               ` Ben Hutchings
2016-11-29  2:31                                 ` Nicholas Piggin
2016-11-29  9:14                                   ` Michal Marek
2016-11-29  4:08                                 ` Linus Torvalds
2016-11-29 13:19                                   ` Adam Borowski
2016-11-29 13:29                                     ` Ingo Molnar
2016-11-29 14:24                                       ` Adam Borowski
2016-11-29 13:51                                     ` Adam Borowski
     [not found]                                       ` <CA+55aFyZiB4YkwvqzrXO=HD8bcnc2xHkAYrek2QHVnhVvAi3Fw@mail.gmail.com>
2016-11-29 16:03                                         ` Michal Marek
2016-11-29 16:17                                           ` Linus Torvalds
2016-11-29 19:57                                             ` Ben Hutchings
2016-11-29 20:35                                               ` Linus Torvalds
2016-11-30 18:18                                                 ` Nicholas Piggin
2016-11-30 18:40                                                   ` Linus Torvalds
2016-11-30 21:33                                                     ` Ben Hutchings
2016-12-01  1:55                                                       ` Nicholas Piggin
2016-12-01  2:35                                                         ` Ben Hutchings
2016-12-01  3:39                                                           ` Nicholas Piggin
2016-12-01 16:12                                                             ` Michal Marek
2016-12-02 14:36                                                               ` Hannes Frederic Sowa
2016-12-09  3:33                                                               ` Nicholas Piggin
2016-12-09 15:21                                                                 ` Ian Campbell
2016-12-09 16:15                                                                   ` Nicholas Piggin
2016-12-09 22:46                                                                     ` Dodji Seketeli
2016-12-10 12:41                                                                       ` Greg Kroah-Hartman
2016-12-12  3:50                                                                         ` Nicholas Piggin
2016-12-12  9:08                                                                         ` Ian Campbell
2016-12-14 17:59                                                                         ` Don Zickus
2016-12-13  1:07                                                                       ` Stanislav Kozina
2016-12-13 22:51                                                                       ` Michal Marek
2016-12-14  8:58                                                                         ` Dodji Seketeli
2016-12-14  9:15                                                                           ` Michal Marek
2016-12-14  9:36                                                                             ` Dodji Seketeli
2016-12-14  9:44                                                                               ` Michal Marek
2016-12-14 10:02                                                                                 ` Dodji Seketeli
2016-12-14 10:15                                                                                   ` Michal Marek
2016-12-14  9:56                                                                               ` Dodji Seketeli
2016-12-14  9:37                                                                             ` Michal Marek
2016-12-01  4:13                                                     ` Don Zickus
2016-12-01  4:32                                                       ` Nicholas Piggin
2016-12-01 15:20                                                         ` Don Zickus
2016-12-01 15:26                                                           ` Christoph Hellwig
2016-12-01 15:40                                                             ` Don Zickus
2016-12-01 16:06                                                               ` Greg Kroah-Hartman
2016-12-01 18:42                                                                 ` Don Zickus
2016-12-09  3:50                                                           ` Nicholas Piggin
2016-12-09  7:55                                                             ` Stanislav Kozina
2016-12-09  8:14                                                               ` Nicholas Piggin
2016-12-09 14:36                                                                 ` Stanislav Kozina
2016-12-09 15:56                                                                   ` Nicholas Piggin
2016-12-09 16:03                                                                     ` Greg Kroah-Hartman
2016-12-12  9:48                                                                       ` Stanislav Kozina
2016-12-13  7:25                                                                         ` Nicholas Piggin
2016-12-14 14:04                                                                       ` Hannes Frederic Sowa
2016-12-15  2:06                                                                         ` Nicholas Piggin
2016-12-15 11:19                                                                           ` Hannes Frederic Sowa
2016-12-15 12:03                                                                             ` Nicholas Piggin
2016-12-15 13:15                                                                               ` Hannes Frederic Sowa
2016-12-15 14:15                                                                                 ` Nicholas Piggin
2016-12-15 15:17                                                                                   ` Hannes Frederic Sowa
2016-12-15 13:35                                                                               ` Stanislav Kozina
2016-12-09 16:16                                                             ` Don Zickus
2016-12-01 10:48                                                       ` Stanislav Kozina
2016-12-01 11:09                                                         ` Nicholas Piggin
2016-12-01 11:33                                                           ` Stanislav Kozina
2016-12-01 12:39                                                             ` Nicholas Piggin
2016-12-01 15:19                                                           ` Dodji Seketeli
2016-12-01 16:14                                                       ` Michal Marek
2016-11-29 17:05                                         ` Adam Borowski
2016-11-29 17:10                                           ` Linus Torvalds
2016-11-29 17:14                                             ` Linus Torvalds
2016-12-01 13:58                                               ` Arnd Bergmann
2016-12-01 16:21                                                 ` Michal Marek
2016-12-01 18:26                                                 ` Linus Torvalds
2016-12-02 10:55                                                   ` Arnd Bergmann
2016-12-02 12:40                                                     ` [RFC, PATCH, v3.9] default exported asm symbols to zero Arnd Bergmann
2016-12-02 12:59                                                       ` Geert Uytterhoeven
2016-12-02 14:51                                                         ` Arnd Bergmann
2016-12-02 15:35                                                       ` Adam Borowski
2016-12-03  4:36                                                       ` Ben Hutchings
2016-12-03 10:43                                                         ` Arnd Bergmann
2016-12-02 17:04                                                     ` [PATCH] x86/kbuild: enable modversions for symbols exported from asm Linus Torvalds
2016-12-04  7:44                                                     ` Alan Modra
2016-12-04 20:44                                                       ` Linus Torvalds
2016-11-29 21:23                                             ` Michal Marek
2016-11-24  9:25           ` Michal Marek
2016-11-24 11:42         ` Regression: " Kalle Valo
2016-11-23 23:07       ` BUG: 4.9-rc6 Still "no symbol version" on boot Philip Müller
2016-11-28 17:10         ` Robert LeBlanc

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