If libmagick* libraries are native code (C, C++, etc.) no, they won’t work if you install them via “apt-get install” or “apt-get download + dpkg -i” on the My Cloud, you have to rebuild them.
If they are written in interpreted languages or they are just made up of atchitecture-neutral artifacts, they will work.
The rule of thumb is: do those package file full names contain “armhf” architecture indication? If so, you have to rebuild them, otherwise if they are marked as “all” you actually don’t need to rebuild them.
Honestly, I didn’t follow your problem in much detail, but from what I have understood, the situation might be this.
WD My Cloud has a Debian Wheezy on it. So, only package versions taken from wheezy repositories are guaranteed to work. So, if you can build and install the libraries you need once taken from wheezy, you’re on the good path.
Taking packages from Jessie and install them on a Wheezy system is not guaranteed to work: even if you are able to build them, once you try to install you may have unsatisfied dependencies, because your packages might depend on newer versions of other packages that are not available on your Wheezy system. The solution is to build also those dependency packages, taken from Jessie, and hope that they will install correctly, because the same problem might occur in a recursive way. In the worst case, your package might require to upgrade the whole system (or a relevant amount of critical/base packages), with the following consequences:
- the system might become unstable: let’s remember that Wheezy is the current stable Debian version, Jessie is still testing
- the system might not work at all, because even if you had the skills to rebuild and install all the required dependencies, it’s hard to say whether the final result will actually work or not, since testing at Debian is performed on either Whezzy or Jessie and not on a hybrid set of mixed package versions
So, my suggestion is: build and install packages from wheezy. If the wheezy version of your package from wheezy is too old, you can either make do with it or, if you’ve nothing to lose, you may experimenti with rebuilding the package all of its dependencies from Jessie, but be prepared to have to revive your WD My Cloud if something goes really wrong.
To add more to this picture, consider that there are some packages that won’t build at all (from either wheezy or jessie suites) because there are problems with QEMU, which is the emulation layer that is used to build these ARM packages on a x86/x64 system (your PC, or virtual machine on your PC). For these problems, which are usually revelead by “segmentation fault” errors at build time, there’s currently no solution. An alternative would be to prepare a build environment directly on the WD My Cloud, but:
- all the required build tools (compilers, etc.) must be built and installed prior for this to work, because of the 64k modification
- it might take very loooong to build some packages on an ARM device (given that it often takes hours even on a real PC!)
- the RAM on the device might be small to build some huge packages, unless you set up a lot of (slooooow) swap space
In short, it is a great hassle…
Hope this helps a bit to clarify the situation.