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Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm

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On Thu, 24 Nov 2016 10:32:12 +0100
Michal Marek <mmarek@suse.com> wrote:

> On 2016-11-24 08:53, Nicholas Piggin wrote:
> > On Thu, 24 Nov 2016 08:36:39 +0100
> > Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> >   
> >> 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?  
> > 
> > Yeah just have EXPORT_SYMBOL take another parameter which attaches a version
> > number and use that as the value for the __crc_ symbol versions rather than
> > a calculated CRC.  
> 
> The problem is that with every kernel release, the structures change in
> a way that you would have to bump the version of virtually every export.
>
> At which point, there would be little difference between
> CONFIG_MODVERSION on and off (without CONFIG_MODVERSION, we compare the
> kernel version strings when loading modules).


I'm not sure about that. If they are truly incompatible changes and
MODVERSIONS does not pick up a different CRC, then it's even worse if
incompatible modules are missed so often.

Thanks,
Nick

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Re: BUG: 4.9-rc6 Still "no symbol version" on boot Philip Müller <philm@manjaro.org> - 2016-11-23 21:10 +0100
  Re: BUG: 4.9-rc6 Still "no symbol version" on boot Robert LeBlanc <robert@leblancnet.us> - 2016-11-23 21:20 +0100
    Re: BUG: 4.9-rc6 Still "no symbol version" on boot Philip Müller <philm@manjaro.org> - 2016-11-23 21:30 +0100
  Re: BUG: 4.9-rc6 Still "no symbol version" on boot Adam Borowski <kilobyte@angband.pl> - 2016-11-23 22:00 +0100
    Re: BUG: 4.9-rc6 Still "no symbol version" on boot Robert LeBlanc <robert@leblancnet.us> - 2016-11-23 22:10 +0100
    [PATCH] x86/kbuild: enable modversions for symbols exported from asm Adam Borowski <kilobyte@angband.pl> - 2016-11-23 23:10 +0100
      Re: [PATCH] x86/kbuild: enable modversions for symbols exported from  asm Philip Müller <philm@manjaro.org> - 2016-11-24 00:20 +0100
      Re: [PATCH] x86/kbuild: enable modversions for symbols exported from  asm Ingo Molnar <mingo@kernel.org> - 2016-11-24 06:10 +0100
        Re: [PATCH] x86/kbuild: enable modversions for symbols exported  from asm Nicholas Piggin <npiggin@gmail.com> - 2016-11-24 06:30 +0100
          Re: [PATCH] x86/kbuild: enable modversions for symbols exported from  asm Ingo Molnar <mingo@kernel.org> - 2016-11-24 07:10 +0100
            Re: [PATCH] x86/kbuild: enable modversions for symbols exported  from asm Nicholas Piggin <npiggin@gmail.com> - 2016-11-24 08:30 +0100
              Re: [PATCH] x86/kbuild: enable modversions for symbols exported from  asm Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-24 08:40 +0100
                Re: [PATCH] x86/kbuild: enable modversions for symbols exported  from asm Nicholas Piggin <npiggin@gmail.com> - 2016-11-24 09:00 +0100
                Re: [PATCH] x86/kbuild: enable modversions for symbols exported from  asm Michal Marek <mmarek@suse.com> - 2016-11-24 10:40 +0100
                Re: [PATCH] x86/kbuild: enable modversions for symbols exported  from asm Nicholas Piggin <npiggin@gmail.com> - 2016-11-24 11:10 +0100
                Re: [PATCH] x86/kbuild: enable modversions for symbols exported from  asm Michal Marek <mmarek@suse.com> - 2016-11-24 12:00 +0100
                Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm Arnd Bergmann <arnd@arndb.de> - 2016-11-24 10:50 +0100
                Re: [PATCH] x86/kbuild: enable modversions for symbols exported  from asm Nicholas Piggin <npiggin@gmail.com> - 2016-11-24 11:10 +0100
                Re: [PATCH] x86/kbuild: enable modversions for symbols exported from  asm Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-24 11:00 +0100
                Re: [PATCH] x86/kbuild: enable modversions for symbols exported  from asm Nicholas Piggin <npiggin@gmail.com> - 2016-11-24 11:40 +0100
                Re: [PATCH] x86/kbuild: enable modversions for symbols exported from  asm Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-24 16:30 +0100
                Re: [PATCH] x86/kbuild: enable modversions for symbols exported  from asm Nicholas Piggin <npiggin@gmail.com> - 2016-11-25 01:50 +0100
        Re: [PATCH] x86/kbuild: enable modversions for symbols exported from  asm Michal Marek <mmarek@suse.com> - 2016-11-24 10:30 +0100
      Regression: Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm Kalle Valo <kvalo@codeaurora.org> - 2016-11-24 12:50 +0100
    Re: BUG: 4.9-rc6 Still "no symbol version" on boot Philip Müller <philm@manjaro.org> - 2016-11-24 00:10 +0100

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