ru.unix.bsd

 
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 From : Slawa Olhovchenkov                   2:5030/500     13 Mar 2006  12:38:30
 To : All
 Subject : Вести с полей
 -------------------------------------------------------------------------------- 
 

 
 From: Daniel Eischen <eischen@vigrid.com>
 Subject: RFC: Symbol versioning for libc
 
 I've been working on symbol versioning libc and have a patch
 that seems to work.  It's been tested on x86 with build &
 install world, KDE, mozilla, and firefox, but there may be
 some problems I haven't found yet.  These would likely result
 in undefined symbol errors from libraries or applications.
 
 I'd like to commit what I have to enable wider testing, but
 turn off symbol versioning by default.  I would also like
 re@ to take a look at the version namespace scheme.  The
 following was derived from Sun's convention.
 
     FBSD_1.0 (FBSD_X.Y[.Z])
         This is the first rev of the public namespace for
         libc and related libraries.  For every minor
         release of FreeBSD, starting with 7.0, the minor
         version of the namespace will be bumped if there
         is an ABI change.  The version is bumped as soon
         as the first ABI change hits the tree.  If there
         are no ABI changes, a minor-minor (subminer?)
         version (Z) can be added (or bumped) to denote a
         release, performance improvement, etc.
 
     FBSDprivate_1.0 (FBSDprivate_X.Y)
         This is our private namespace.  Any symbols that
         need to be visible outside of libc (or any other
         versioned library) that are only meant for use by
         our own libraries or applications are listed in
         this namespace.  For instance, _spinlock() which
         is overridden in libc by the thread libraries, or
         libc's __pw_scan() or __use_pts() which are used
         by libutil.  This is initially given a version
         number, but is not bumped after introducing private
         ABI changes or within release cycles.  We provide
         a complete system built from a consistent set or
         sources, so there is no real need to maintain
         ABI in this namespace.  However, since our first
         release may need to be compatible with older libraries
         built before symbol versioning, it may require us
         to provide at least one additional version.
 
 The two namespaces allow us to write simple ABI-checking
 tools (readelf -s application | grep "FreeBSDprivate") that
 3rd-party developers can use to certify compliance with our
 ABI.  We (FreeBSD) will give no guarantees about anything
 within the FreeBSDprivate version namespace; symbols within
 that namespace may come and go within release cycles.
 
 The proposed numbering scheme would be something along the
 lines of this (in linker map format and in chronological order):
 
   # Release 7.0
   FBSD_1.0 {
   };
 
   FBSDprivate_1.0 {
   };
 
   # Release 7.1 - no ABI changes, depends on FBSD_1.0
   FBSD_1.0.1 {
   } FBSD_1.0;
 
   # Release 7.2 - with ABI changes, depends on FBSD_1.0
   # There is no benefit to depending on 1.0.1 since there
   # are no ABI changes to inherit.
   FBSD_1.1 {
   } FBSD_1.0;
 
   # Release 8.0 - with or without ABI changes
   # This was branched from release 7.2.  It could just as
   # well have been branched from 7.0 or 7.1.
   FBSD_2.0 {
   } FBSD_1.1;
 
   # Release 7.3 - without ABI changes, depends on FBSD_1.1
   FBSD_1.1.1 {
   } FBSD_1.1;
 
   # Release 7.4 - with ABI changes, depends on FBSD_1.1
   FBSD_1.2 {
   } FBSD_1.1;
 
   # Release 8.1 - with ABI changes, depends on FBSD_2.0
   FBSD_2.1 {
   } FBSD_2.0;
 
   ...
 
 The latest patch is here:
 
   http://people.freebsd.org/~deischen/symver/symver.diffs.030706
 
 There's a brief description of symbol versioning here:
 
   http://people.freebsd.org/~deischen/symver/library_versioning.txt
 
 and you can find some other documents at:
 
   http://docs.sun.com/app/docs/doc/817-1984
   http://people.redhat.com/~drepper/symbol-versioning
 
 or google.
 ... Смотри в корень!
 --- GoldED+/BSD 1.1.5
  * Origin:  (2:5030/500)
 
 

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