Module building oddities with <module>-objs under Kernel 2.6.8.1

Module building oddities with <module>-objs under Kernel 2.6.8.1

[Andre Bonin]

Hey all,
I have a simple module in datasim.c and several service functions in 
another file status.c

The module compiles fine (no warnings) with the following Makefile, but 
the printk function doesn't seem to output anything.  The output doesn't 
show with dmesg, tail -f /var/message and everything else I tried.

The same code works fine if copy-pasted inside the datasim.c module (and 
not compiled using datasim-objs: in the makefile).  It also works fine 
if i do the ugly thing of (*shudder*)  #include "status.c"

/usr/bin/nm datasim.ko yields "U    printk".

I know the entry points get called properly because the module is 
loaded, and functions after the printk's that set up sysfs attributes 
are successfull (and appear under sysfs).

I find it odd that if i compile with the datasim-objs stuff that i can't 
view the printk, but if i comment it out and do #include "datasim.c" it 
works fine. 

Thanks

Here is the Makefile.
----------------------------------------------------
KDIR         := /usr/src/linux
PWD          := $(shell pwd)

obj-m        += datasim.o
datasim-objs := status.o

all:
    $(MAKE) -C $(KDIR) SUBDIRS=$(PWD)

clean:
    rm -rf *.o
    rm -rf *.ko
    rm -rf *.mod.c
    rm -rf .datasim*
    rm -rf .built-in.o.cmd
    rm -rf *~
    rm -rf *.cache
    sudo rm -rf .tmp_versions
install:
    sudo /sbin/insmod datasim.ko
uninstall:
    sudo /sbin/rmmod datasim.ko
TAGS:
    etags *.c   

Re: Module building oddities with <module>-objs under Kernel 2.6.8.1

[Sam Ravnborg]

On Sat, Oct 02, 2004 at 01:13:54AM -0400, Andre Bonin wrote:
> Here is the Makefile.

It is preferred to guard the kbuild specific stuff inside
ifeq ($(KERNELRELEASE),)
Normal stuff
else
kbuild stuff
endif

> ----------------------------------------------------
> KDIR         := /usr/src/linux
> PWD          := $(shell pwd)
> 
> obj-m        += datasim.o
> datasim-objs := status.o
This is wrong, you cannot use same name for a .o file and the final module.

Name your .c file datasim_core.c or similar and use:
obj-m        := datasim.o
datasim-objs := datasim_core.o status.o

	Sam