The run-time linker doesn't deal with magic symlinks (or even plain symlinks) for shared objects?

[Johan Ihren <johani%johani.org@localhost>]

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I want to use the @machine magic symlink to be able to install both  
i386 and amd64 distributions into the same root.

The primary reason is that I run NetBSD/i386 Xen3 in production, which  
requires a release version, but I'm porting my stuff to NetBSD/amd64  
Xen3, which is only available as -current. Being able to choose at  
boot time which one to run would be *very* convenient, especially for  
laptops with only one disk.

However, this just plain doesn't work. If I move /lib to a location  
which is the target of a magic symlink /sbin/init refuses to execute  
("Error 2"). Having /sbin itself as /sbin --> /machine/@machine/sbin  
seems to work fine, though. Leaving /lib alone to allow the machine to  
reach multiuser the following is an obvious example of the problem:

- -bash-3.2# pwd
/usr
- -bash-3.2# uname -m
amd64
- -bash-3.2# type uname
uname is hashed (/usr/bin/uname)
- -bash-3.2# mv /usr/lib /usr/machine/amd64/lib
- -bash-3.2# ln -s machine/@machine/lib /usr
- -bash-3.2# uname -m
Shared object "libc.so.12" not found
- -bash-3.2# rm lib
- -bash-3.2# mv machine/amd64/lib /usr
- -bash-3.2# uname -m
amd64

Note #1: yes, I've built custom kernels with "options MAGICLINKS", so  
not doing "sysctl -w vfs.generic.magiclinks=1" early enough is not the  
problem.

Note #2: I admit that I don't understand where the problem lies. I  
thought that magic symlink support was entirely inside the kernel and  
that the run-time linker being a userland process should deal with the  
magic sylinks just like every other process, i.e. bascially not even  
noticing. What am I missing?

Note #3: Umm, I just realized that this has nothing to do with magic  
symlinks as such. It breaks just as nicely with plain ordinary symlinks.

Note #4: yes, I realize that even with the @machine magic symlink  
working, there may be other stumbling blocks around the corner.

Regards,

Johan

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