Subject: Re: [PATCH] x86/kbuild: enable modversions for symbols exported from
 asm
To: Dodji Seketeli <dodji@seketeli.org>
References: <20161201125545.406d092c@roar.ozlabs.ibm.com>
 <1480559754.16599.92.camel@decadent.org.uk>
 <20161201143928.07a08348@roar.ozlabs.ibm.com>
 <6e8cf20b-2d2f-ba1f-e02c-c757d5a25db7@suse.com>
 <20161209133308.0acbb57a@roar.ozlabs.ibm.com>
 <1481296893.4509.135.camel@hellion.org.uk>
 <20161210021529.4a6e684f@roar.ozlabs.ibm.com> <86vaus3eld.fsf@seketeli.org>
 <f7c5d50d-8930-7ab1-62bb-8a5d0aead988@suse.com> <867f72vqec.fsf@seketeli.org>
 <20161214091539.GA9000@sepie.suse.cz> <86twa6svhi.fsf@seketeli.org>
 <a3cd76cb-48ac-5d86-0a82-ac7b11738813@suse.com> <86y3zirfpq.fsf@seketeli.org>
Cc: Nicholas Piggin <npiggin@gmail.com>, Ian Campbell <ijc@hellion.org.uk>,
        Ben Hutchings <ben@decadent.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Adam Borowski <kilobyte@angband.pl>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Debian kernel maintainers <debian-kernel@lists.debian.org>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
From: Michal Marek <mmarek@suse.com>
Message-ID: <3bb2d553-8f3c-d58b-d646-9a3609286260@suse.com>
Date: Wed, 14 Dec 2016 11:15:07 +0100
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On 2016-12-14 11:02, Dodji Seketeli wrote:
> Michal Marek <mmarek@suse.com> a écrit:
> 
>>> Libabigail does a "whole binary" analysis of types.
>>>
>>> So, consider the point of use of the type 'struct s1*'.  Even if 'struct
>>> s' is just forward-declared at that point, the declaration of struct s1
>>> is "resolved" to its definition.  Even if the definition comes later in
>>> the binary.
>>
>> But there isn't any definition of struct s1 in t1.o. Does abidiff
>> "steal" the definition from the other object file? That would be
>> legitimate, I'm just curious.
> 
> If there is another translation unit in the *same* binary that defines
> struct s1, then yes, it's "stolen", as you say.
> 
> But if in the entire binary, struct s1 is just declared (not defined),
> then it'll compare equal to any struct s1 that is defined in the
> *second* binary.

That makes sense, thanks.

Michal