MySQL Bugs: #35743: Dynamic plugins fail to load on i5/OS

Bug #35743	Dynamic plugins fail to load on i5/OS
Submitted:	1 Apr 2008 15:42	Modified:	29 Sep 2008 17:37
Reporter:	Tim Clark	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Compiling	Severity:	S2 (Serious)
Version:	5.1.23	OS:	Other (i5/OS v5r4)
Assigned to:	Kent Boortz	CPU Architecture:	Any
Tags:	plugin, rtld, unresolved symbol

Description:
Attempting to install a dynamic plugin on i5/OS causes the following error:

mysql> install plugin example soname "ha_example.so"; 
ERROR 1126 (HY000): Can't open shared library '/usr/local/mysql-5.1.23-rc-i5os-p
ower-32bit/lib/ha_example.so' (errno: 8 rtld: 0712-001 Symbol clone__7handlerFP1
1st_mem_root was referenced
      from module /usr/local/mysql-5.1.23-rc-i5os-power-32bi)

This looks similar to Bug #30296, in that the symbols in the mysqld executable are not exported by default. The dynamic plugin depends on some of the symbols defined in mysqld, but dump -Tv mysqld reveals no exported symbols.

This bug may also affect AIX, since i5/OS PASE and AIX have a common loader.

How to repeat:
install plugin example soname "ha_example.so"; 

Suggested fix:
One possible fix is to set LDFLAGS="-Wl,-bexpall" when building mysqld.

verified on support i5.

In order to resolve to all of the symbols (including those preceded by an underscore "_" (e.g. _hash_init), expfull must be specified instead of expall.

This can be done with the following configure option:
--with-mysqld-ldflags=-Wl,-bexpfull

This affects plugins which rely on some internal functions (like _hash_init, as indicated above.)

The build scripts were changed to provide the flag "-Wl,-bexpfull" to the
linker to include also symbols that are prefixed with an underscore.
The flag will be used for the 5.0.72, 5.1.29 and 6.0.8 builds.

Noted in 5.0.72, 5.1.29, 6.0.8 changelogs.

Dynamic plugins failed to load on i5/OS.