Re: sys_sem* undefined

[Paulo Marques <pmarques@grupopie.com>]

Arne Henrichsen wrote:
> Hi Randy,
> 
> thanks for the help. I am very new to Linux
> programming, and I do not understand what you mean
> with  'syscalls are not called by name'. 
> 
> I did find the header file syscalls.h, recompiled my
> code but it still says the following:
> 
> *** Warning: "sys_semop"
> [/prj/builds/host/linux/prj.ko] undefined!
> *** Warning: "sys_semctl"
> [/prj/builds/host/linux/prj.ko] undefined!
> *** Warning: "sys_semget"
> [/prj/builds/host/linux/prj.ko] undefined!
> 
> And when I load the module, then it tells me:
> 
> insmod: error inserting './prj.ko': -1 Unknown symbol
> in module
> 
> So, I call sys_sem* functions from my code. What else
> must I do?

Syscalls are supposed to be called from userspace, so that the kernel 
does something on behalf of an application.

Some syscalls have their do_<syscall name> equivalent because it makes 
sense to call them from inside the kernel, but others don't.

If you want to use semaphores inside the kernel I suggest you read the 
Rusty Rusell's Unreliable Guide to Kernel Locking first:

http://wwwos.inf.tu-dresden.de/~ch12/diplom/DocBook/kernel-locking/

I hope this helps,

-- 
Paulo Marques - www.grupopie.com