Re: Recent changes in dpkg

2010-05-27 Thread Jonas Smedegaard

On Thu, May 27, 2010 at 02:13:16AM -0400, Felipe Sateler wrote:

On 24/05/10 05:05, Raphael Hertzog wrote:

  * dpkg-gensymbols offers new ways to manage symbols files (matching C++
symbols by their demangled name, matching symbols with regular
expressions) thanks to Modestas Vainius.


This should be useful for people using symbols files.


Yep.  Already looked at it for JACK when that new dpkg was released.

I see no real use for it there, until we have some knowledge on which 
symbols are actually the official ones across implementations of JACK.


For now I simply assume that if a symbol changes in a new release then 
it is sane (but the fact that it changes is then noticed and tracked 
through our git, if the assumption turns out to be wrong).  And I have 
lowered to only warn when most changes occur.


In other words, the symbols file is not used as the intended rigid 
safety net, but rather as a log to help understand problems *after* they 
occur.  This hopefully changes in the future by me or others gaining 
more knowledge in the symbols officially needed by JACK.



 - Jonas

--
 * Jonas Smedegaard - idealist  Internet-arkitekt
 * Tlf.: +45 40843136  Website: http://dr.jones.dk/

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Re: Recent changes in dpkg

2010-05-27 Thread Dmitrijs Ledkovs
On 27 May 2010 07:13, Felipe Sateler fsate...@gmail.com wrote:
 On 24/05/10 05:05, Raphael Hertzog wrote:

   * dpkg-gensymbols offers new ways to manage symbols files (matching C++
     symbols by their demangled name, matching symbols with regular
     expressions) thanks to Modestas Vainius.

 This should be useful for people using symbols files.


Thanks for the heads up. I will try this out with one of my libraries.
It would be interesting to generate symbols for a few versions and to
check weather api/abi was broken.

API is easy (function removed or arguments changed) what about ABI is
there a rule of thumb for that?



 --
 Saludos,
 Felipe Sateler

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Re: Recent changes in dpkg

2010-05-27 Thread Reinhard Tartler
On Do, Mai 27, 2010 at 10:02:31 (CEST), Jonas Smedegaard wrote:

 On Thu, May 27, 2010 at 02:13:16AM -0400, Felipe Sateler wrote:
On 24/05/10 05:05, Raphael Hertzog wrote:
   * dpkg-gensymbols offers new ways to manage symbols files (matching C++
 symbols by their demangled name, matching symbols with regular
 expressions) thanks to Modestas Vainius.

This should be useful for people using symbols files.

 Yep.  Already looked at it for JACK when that new dpkg was released.

 I see no real use for it there, until we have some knowledge on which
 symbols are actually the official ones across implementations of JACK.

Without knowing that, I don't think that using symbols file has much
benefit.

 For now I simply assume that if a symbol changes in a new release then
 it is sane (but the fact that it changes is then noticed and tracked
 through our git, if the assumption turns out to be wrong).  And I have
 lowered to only warn when most changes occur.

So you have effectively turned the dpkg-gensymbols mechanism to a source
of noise in form of warnings which are of no use since you don't know
what symbols are supposed to be public and what not.

 In other words, the symbols file is not used as the intended rigid
 safety net, but rather as a log to help understand problems *after* they
 occur.  This hopefully changes in the future by me or others gaining
 more knowledge in the symbols officially needed by JACK.

understanding problems after they occur? For this the service
snapshot.debian.org is a far better tool than symbol files.

BTW, this is exactly the reason why I had concerns at the time symbol
files were introduced. Currently it is an additional (mandatory?) tool
that increases the complexity of the package without direct (real)
benefit. For investigating and comparing exported symbols, I'd suggest
to use nm(1) or objectdump(1) with diff(1). In my eyes, dpkg-gensymbols
is just a tool that a) integrates these tools to the build process and
b) define an additional workflow for package upgrades.

As for the part [having] some knowledge on which symbols are actually the
official ones across implementations of JACK - that's actually crystal
clearly defined by the jack API documentation. We have already noticed
that there are tons of additional symbols being exported by jackd2 that
should better be hidden. Adi has spoken to upstream to hide them, but
AFAIUI that didn't lead to anything.


-- 
Gruesse/greetings,
Reinhard Tartler, KeyID 945348A4

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