Re: ld.so for multiarch and multilib installed at same time

[Yunqiang Su <wzssyqa@gmail.com>]

On Fri, Apr 25, 2014 at 5:58 PM, Steve McIntyre <steve@einval.com> wrote:
> Yunqiang Su wrote:
>>On amd64 system:
>>
>> libc6-i386  make /lib/ld-linux.so.2  link to /lib32/ld-linux.so.2 and link to
>>       /lib32/ld-2.18.so
>>
>>libc6:i386 make /lib/ld-linux.so.2 link to /lib/i386-linux-gnu/ld-2.18.so
>>
>>when these 2 packages installed at the same time
>>     /lib/ld-linux.so.2 is linked to /lib/i386-linux-gnu/ld-2.18.so
>>
>>And dpkg is happy about that this happens.
>
> What's responsible for making the links? Are they directly in the
> package, or made by postinst etc.? Are the 2 packages sensible in
> terms of multi-arch setup?

ldso is the load of binary, it is the entrance of any binary execution.
On any system, it is fixed

please see:
https://wiki.debian.org/Multiarch/LibraryPathOverview#ELF interpreter

It is directly in these packages.

>
>>On mips64el system:
>>
>>libc6-mips32 make /lib/ld.so.1 link to /lib/ld-2.18.so
>>         (yes, quite strange, mips system asks for use /lib as o32
>>multilib path)
>
> Meh, it's not doing the braindead /lib32 thing. That shouldn't be a
> problem. :-)

lib32 is left for n32 multilib on mips* systems.

>
>>libc6:mipsel make /lib/ld.so.1 link to /lib/mipsel-linux-gnu/ld-2.18.so
>>
>>When try to install these 2 packages both, dpkg will be unhappy:
>>
>>dpkg: error processing archive libc6_2.18-4_mipsel.deb (--install):
>> trying to overwrite '/lib/ld.so.1', which is also in package
>>libc6-mips32 2.18-4
>>Errors were encountered while processing:
>>
>>
>>I also tried to repack libc6:mipsel to link /lib/ld.so.1 to
>>/lib/mipsel-linux-gnu/ld.so.1
>>instead of ld-2.18.so directly.
>>It aslo has the same problem.
>
> Well, you're still trying to replace the same file (link) on
> disk. dpkg is not going to be happy with that, unless they're
> consistent for multi-arch.
>

The problems is why on amd64, dpkg is happy about it?

> --
> Steve McIntyre, Cambridge, UK.                                steve@einval.com
> Support the Campaign for Audiovisual Free Expression: http://www.eff.org/cafe/



-- 
Yunqiang Su