evain.net - Linking all the way down

Do you remember this post? If you do so, I'm sure you know, what I'm going to show you. A formidable use of the new linker. What do you need? First you need an application. I've reused a very small program I wrote a bunch of month with db4o. It simply allows you to persist a few objects Person in a db4o database, and to retrieve them. But it's sooo cool that I'd like to make it a standalone application. It has a very friendly command line interface:

Very nice isn't it? So now, let's link it so that I have the minimum set of the assemblies my program use.

jbevain@avalon:/tmp/linker$ mono linker.exe -o persons -a persons.exe -p false
jbevain@avalon:/tmp/linker$ cp persons.yap persons/
jbevain@avalon:/tmp/linker$ cd persons/

The yap file is db4o's database. Please note that in SVN, I've disabled the ability to link the assembly mscorlib.dll. It's a very special assembly which is of course very close to the runtime. So if ever you want to remove stuff from it, you have to be very frugal, so you don't remove stuff used within the runtime. And it seems that I've not identified everything used. So it tend to be pretty unstable :) But for the time being, it's fine. Now, let's create a standalone application from this great piece of code.

jbevain@avalon:/tmp/linker/persons$ mkbundle
OS is: Linux
Sources: 0 Auto-dependencies: False
Usage is: mkbundle [options] assembly1 [assembly2...]

Options:
    -c              Produce stub only, do not compile
    -o out          Specifies output filename
    -oo obj         Specifies output filename for helper object file
    -L path         Adds `path' to the search path for assemblies
    --nodeps        Turns off automatic dependency embedding (default)
    --deps          Turns on automatic dependency embedding
    --keeptemp      Keeps the temporary files
    --config F      Bundle system config file `F'
    --config-dir D  Set MONO_CFG_DIR to `D'
    --static        Statically link to mono libs
    -z          Compress the assemblies before embedding.

jbevain@avalon:/tmp/linker/persons$ mkbundle -o persons --nodeps ./persons.exe ./db4o.dll ./mscorlib.dll
OS is: Linux
Sources: 3 Auto-dependencies: False
   embedding: /tmp/linker/persons/persons.exe
   embedding: /tmp/linker/persons/db4o.dll
   embedding: /tmp/linker/persons/mscorlib.dll
Compiling:
as -o /tmp/tmp47dda943.tmp.o temp.s
cc -ggdb -o persons -Wall temp.c `pkg-config --cflags --libs mono`  /tmp/tmp47dda943.tmp.o
Done
jbevain@avalon:/tmp/linker/persons$ mkdir standalone
jbevain@avalon:/tmp/linker/persons$ mv persons standalone/
jbevain@avalon:/tmp/linker/persons$ mv persons.yap standalone/
jbevain@avalon:/tmp/linker/persons$ cd standalone/
jbevain@avalon:/tmp/linker/persons/standalone$ ./persons
Persons manager
l
All persons:
Person, name: Anaelle, age: 19
Person, name: Jb Evain, age: 23
Person, name: Reg, age: 24
q
jbevain@avalon:/tmp/linker/persons/standalone$

Et voil� , we now have a standalone application that works like a charm, and which contains, well almost, only what's needed to use it. That's so great! Ok, let's go back to the code, I need to make the linking against corlib working.

Linking all the way down 22 Aug 2006