libpthread.so.2 compatibility

[Daniel Eischen]

On Mon, 5 Jun 2006, John Hay wrote:
>>
>> How old was your system when you upgraded to -current?  There
>> were changes to malloc() in libc.so.6 which have been in -current
>> for a while, and libpthread is dependent on some internal locks
>> in libc.  If you are using a libc.so.6 before jasone's malloc()
>> changes and a newer libpthread, then that won't work.  When you
>> recompile, your binaries will be linked to libc.so.7, and
>> libpthread.so.2 will find the correct locks.  If you don't
>> find the following:
>>
>>   $ readelf -s /lib/libc.so.6 | grep _malloc
>>      275: 0005f65c   139 FUNC    GLOBAL DEFAULT    8 _malloc_postfork
>>      299: 000e96d0     4 OBJECT  GLOBAL DEFAULT   19 _malloc_options
>>      870: 0005f5d0   139 FUNC    GLOBAL DEFAULT    8 _malloc_prefork
>>     2486: 000d1fd8     4 OBJECT  GLOBAL DEFAULT   11 _malloc_message
>>
>> _malloc_postfork and _malloc_prefork in libc.so.6, then that is
>> probably why libpthread is failing.
>
> The libc.so.6 I copied from the -stable box does not have it:
>
> # readelf -s /lib/libc.so.6 | grep _malloc
>   281: 000d78b4     4 OBJECT  GLOBAL DEFAULT   18 _malloc_options
>  1705: 000c0e30     4 OBJECT  GLOBAL DEFAULT   11 __malloc_lock
>  2351: 000c0e2c     4 OBJECT  GLOBAL DEFAULT   11 _malloc_message
>
> But the one from the -current box has it:
>
> # readelf -s /lib/libc.so.6.old  | grep _malloc
>   274: 0005fcd4   113 FUNC    GLOBAL DEFAULT    8 _malloc_postfork
>   297: 000e25d4     4 OBJECT  GLOBAL DEFAULT   19 _malloc_options
>   852: 0005fc60   113 FUNC    GLOBAL DEFAULT    8 _malloc_prefork
>  2424: 000cae38     4 OBJECT  GLOBAL DEFAULT   11 _malloc_message
>
> Does it work for you? Can you take a 6-stable libpthread app and run
> it on current?

No, you can't make a 6-stable libpthread and have it work
on -current.  Both libc and libpthread have to match.  There
were also other changes in libc that libpthread relies on
(__thr_jtable changed in size).

When you upgraded to -current, you got a different libpthread
that is reliant on -current's libc.  But since libc's version
was bumped, you never got a -current libc.so.6 that was
compatible with libpthread.  The only way to get around this
is to go back a couple of weeks to before the resolver
changes and libc bump were committed -- rebuild libc.so.6
from those older sources.

-- 
DE