shared library loading

[Shaun]

hi, guys!

i wanna add elf shared library support to my os. but i found it is really a tough work.
as far as i can know,in kernel space, i should load a .so file called interpreter(in linux, it is ld-linux.so.2) first if i want to load a dynamic linked app. and the problem is:

1,in kernel space, i should build a auxiliary vector that is used by interpreter on app's stack and then call the interpreter's entry point. i wanna know how to build this vector,and what is needed i should supply to interpreter?
i do a little homework looking up linux kernel source code, the create_elf_tables() does these stuff, but it is hard to comprehension. hope someone can give me more details. Spec is also ok.

2,for the interpreter, do i must implement it by my self? can i port some existing ones? glibc contains a shared library loader, uclibc also does, but they all for linux platform, and it's hard to porting. any one has good ideas?


thanks.

[max]

Hey Shaun

I have not done dynamic linking yet, so I can only tell you about some resource I found that might help you. Theres this wiki page about dynamic linking and here is some information on the interpreter.

As far as I can tell you'll have to write your own interpreter binary, because it's specific to your OS (has to lookup the binaries of the searched libraries). Your system design could be entirely different and require different steps for loading the binaries etc.

Greets, Max

[Shaun]

@max

I have not done dynamic linking yet, so I can only tell you about some resource I found that might help you. Theres this wiki page about dynamic linking and here is some information on the interpreter.

great thanks for your effort.

As far as I can tell you'll have to write your own interpreter binary, because it's specific to your OS (has to lookup the binaries of the searched libraries). Your system design could be entirely different and require different steps for loading the binaries etc.

OH,god! it's really a bad news to me.

i think i have met another long long way to go.

[martinFTW]

@max

I have not done dynamic linking yet, so I can only tell you about some resource I found that might help you. Theres this wiki page about dynamic linking and here is some information on the interpreter.

great thanks for your effort.

As far as I can tell you'll have to write your own interpreter binary, because it's specific to your OS (has to lookup the binaries of the searched libraries). Your system design could be entirely different and require different steps for loading the binaries etc.

OH,god! it's really a bad news to me.

i think i have met another long long way to go.

Writing a shared library loader is no big thing. Of course it is probably complicated to generate and write ld.so as shared static lib, but who forces you to do that, I implemented it as a static library which was quite easy (look here: https://github.com/MartinErhardt/Lizarx ... /ld_a/ld.c). The coding style is horrific no comments redundancy in resolve references, also it is not a complete support only I386/X86_64_GLOB_DATA and I386/X86_64_JMP_SLOT bindings, but for me it works(I currently write a ramfs as shared lib)