Comment 2 for bug 34933

I have the same problem. Following packages are installed:
linux-image-2.6.15-20-686 (2.6.15-20.30)
linux-headers-2.6.15-20-686 (2.6.15-20.30)
thinkpad-source (5.8-4)
Compiler version:
gcc version 4.0.3 (Ubuntu 4.0.3-1ubuntu4)
Running kernel:
Linux version 2.6.15-20-686 (buildd@vernadsky) (gcc version 4.0.3 (Ubuntu 4.0.3-1ubuntu3)) #1 SMP PREEMPT Tue Apr 4 18:37:00 UTC 2006

Module build via module-assistant fails.

The output of a manual 'make' inside '/usr/src/modules/thinkpad/2.6/drivers' is:

 make -C /lib/modules/2.6.15-20-686/build SUBDIRS=/usr/src/modules/thinkpad/2.6/drivers modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.15-20-686'
  CC [M] /usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.o
In file included from /usr/src/modules/thinkpad/2.6/drivers/../include/thinkpad_common.h:80,
                 from /usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c:42:
/usr/src/modules/thinkpad/2.6/drivers/../include/rtcmosram.h:171: warning: 'packed' attribute ignored
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c: In function 'apm_bios_call':
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c:208: warning: implicit declaration of function 'get_cpu_ptr'
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c:208: warning: assignment makes pointer from integer without a cast
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c:234: warning: implicit declaration of function 'put_cpu_ptr'
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c: In function 'apm_bios_call_simple':
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c:264: warning: assignment makes pointer from integer without a cast
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c: In function 'thinkpadpm_init':
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c:475: error: 'pm_active' undeclared (first use in this function)
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c:475: error: (Each undeclared identifier is reported only once
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c:475: error: for each function it appears in.)
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c:513: warning: 'inter_module_register' is deprecated (declared at include/linux/module.h:571)
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c: In function 'thinkpadpm_exit':
/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.c:522: warning: 'inter_module_unregister' is deprecated (declared at include/linux/module.h:572)
make[2]: *** [/usr/src/modules/thinkpad/2.6/drivers/thinkpadpm.o] Error 1
make[1]: *** [_module_/usr/src/modules/thinkpad/2.6/drivers] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-2.6.15-20-686'
make: *** [default] Error 2

With package thinkpad-source (5.9-2) from debian sid its working.