rtld enhancement to add osversion sub-directory search

[Doug Ambrisko]

Brooks Davis writes:
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| On Fri, Feb 13, 2009 at 01:08:56PM -0800, Doug Ambrisko wrote:
| > David Schultz writes:
| > | On Thu, Feb 12, 2009, Doug Ambrisko wrote:
| > | > Kostik Belousov writes:
| > | > | There is a popular feature, unfortunately, not supported by FreeBSD
| > | > | ld.so, called Dynamic String Tokens, see
| > | > | http://docs.sun.com/app/docs/doc/817-1984/appendixc-4?l=en&a=view
| > | > | 
| > | > | I have almost abandoned patch that adds support for $ORIGIN, $OSREL,
| > | > | $OSNAME, and $PLATFORM. Quite amazingly, it merged with today CURRENT
| > | > | without serious conflicts.
| > | > | http://people.freebsd.org/~kib/misc/rtld_locks.4.patch
| > | > 
| > | > That is an interesting feature, however, it almost seems backwards for
| > | > me if I understand it correctly.  I need old binaries to find the library 
| > | > it was built with and not new ones based on the base OS.  The plus that 
| > | > I see with their feature is for a library that has been optimized for a 
| > | > specific type of CPU etc.
| > | 
| > | The Solaris rtld features are very useful when you want to
| > | export a volume with a bunch of apps over NFS, and the clients are
| > | running different releases or different architectures. It can
| > | probably also solve your problem if you bother to place different
| > | library versions in different directories and set your library
| > | path appropriately.
| > 
| > Unless I missed something it seems to be an inverse feature to 
| > what I want since it expands based on the current kernel's
| > uname type results.  I need it to expand based on the original OS
| > that it was built on.  I'll have to see if my Solaris box at work
| > has this feature or not.  I can't change LD_LIBRARY_PATH etc.
| > type things.  Doing ldconfig -m of various things doesn't help
| > since that can find the wrong one.  My idea was to do something
| > like what happens for 32bit on 64bit and Linux on FreeBSD in that
| > it looks at osversion specific places then the standard.
| 
| While I commented on the Dynamic String Tokens and think it might be
| useful, that's a distraction for your proposal.  I think you proposal
| sounds useful as well.  If it was in 7 by the time I upgrade my cluster
| from 6, I'd probably use it to ease the transition.

Since my scheme seems useful, then I'll proceed to clean up my patch
some more then send it out for people to play with and comment on.

Thanks,

Doug A.