Gentoo Archives: gentoo-dev

From: Paul de Vrieze <pauldv@g.o>
To: gentoo-dev@l.g.o
Subject: [gentoo-dev] testing for new versions of db.
Date: Wed, 22 Feb 2006 20:49:47
1 Hi all,
3 * if you don't want the explanation, skip to *********
5 I believe I have finally found a solution to the problems that plague berkeley
6 db. While slotting has worked for a long time now, there were serious
7 problems caused by the fact that db is often used within libraries. Some of
8 these libraries namely use different db versions, but end up in the same
9 executable. As a result a symbol collision occurs, and the wrong code is
10 used. Corrupting the databases.
12 To this end db-4.{0,1,2}.x use the --with-uniquename hack. This hack appends
13 some magic string after all symbols and as such makes them unique. This has
14 various drawbacks, including the fact that many configure scripts do not
15 expect this. db-4.3 and db-4.4 do not support this hack any longer. It for
16 example also conflicts with dbxml (also from sleepycat aka oracle).
18 To solve this I've delved into the ld manual pages, performed some tests and
19 found that the linker also has a similar uniquename trick, but performs it
20 much better. It is called symbol versioning, and as long as things go right,
21 it should be completely transparent. If things go wrong, it will signal it
22 instead of using the wrong implementations. Symbol versioning can be done by
23 way of a linking script, but for our purposes much easier, there is a command
24 line option. This option "--default-symver" will use the soname as the
25 version of all unversioned symbols (those that have no other version
26 assigned). This option should be safe to use with almost all libraries, and
27 might be a solution to some problems with libraries being linked twice
28 (libstdc++ anyone).
30 *********
32 Ok, after the explanation, I would like people to test the change. To this I
33 would ask people who do not shy away from more or less serious recompiles to
34 unmask db and merge either db-4.3.29 or db-4.4.20. Both ebuilds should be
35 stable except for upgrade issues. The new changes should fix that.
37 If you want to test upgrade issues specifically, be aware that they only occur
38 when going from db-4.3 to db-4.4 as db-4.2 still uses the uniquename hack.
40 Thanks,
41 Paul
43 ps. Openldap people, the sooner you test, the sooner you get a new db
44 version :-P
46 --
47 Paul de Vrieze
48 Gentoo Developer
49 Mail: pauldv@g.o
50 Homepage: