linking user space and kernel space programs with qmake

[jacek]

I guess I always thought "RT_DAQ:RT_DAQ.c RT_user" was how the two files got linked together. Is this wrong?

Yes, it is. That's only a rule that tells the make program that the "RT_DAQ" target depends on "RT_DAQ.c" and "RT_user" (i.e. it states that if one of them has been changed the RT_DAQ should be rebuilt).

Since you are building two separate things, you could use the subdir template:

Suppose your project directory has following layout:

./rt.pro
./frontend/rt_user.pro
./frontend/RT_user.cpp
./module/Makefile
./module/RT_DAQ.c

Where rt.pro is:

TEMPLATE = subdirs
SUBDIRS += frontend module

TEMPLATE = subdirs
SUBDIRS += frontend module

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./frontend/rt_user.pro is:

TEMPLATE = app
TARGET = ../bin/rt_client
MOC_DIR = ../build
OBJECTS_DIR = ../build
INCLUDEPATH += /usr/src/linux/include \
               /usr/realtime/include \
               /devel/comedi-0.7.68/include \
               /opt/kde3/include
LIBS += -L/opt/kde3/lib -lkdeui -lkdecore \
        -L/devel/comedi-0.7.68/lib -lcomedi
SOURCES += RT_user.cpp

TEMPLATE = app
TARGET = ../bin/rt_client
MOC_DIR = ../build
OBJECTS_DIR = ../build
INCLUDEPATH += /usr/src/linux/include \
               /usr/realtime/include \
               /devel/comedi-0.7.68/include \
               /opt/kde3/include
LIBS += -L/opt/kde3/lib -lkdeui -lkdecore \
        -L/devel/comedi-0.7.68/lib -lcomedi
SOURCES += RT_user.cpp

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and ./module/Makefile is:

LINUXINC= /usr/src/linux/include
RTAIINC= /usr/realtime/include
COMEDIDIR= /devel/comedi-0.7.68/include
FLAGS=-g -D__KERNEL__ -DMODULE -O2
INCLD= -I$(LINUXINC) -I$(RTAIINC) -I/usr/include
 
RT_DAQ: RT_DAQ.c
    gcc  -c $(FLAGS) $(INCLD) -I$(COMEDIDIR) RT_DAQ.c

LINUXINC= /usr/src/linux/include
RTAIINC= /usr/realtime/include
COMEDIDIR= /devel/comedi-0.7.68/include
FLAGS=-g -D__KERNEL__ -DMODULE -O2
INCLD= -I$(LINUXINC) -I$(RTAIINC) -I/usr/include
 
RT_DAQ: RT_DAQ.c
    gcc  -c $(FLAGS) $(INCLD) -I$(COMEDIDIR) RT_DAQ.c

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If all paths are correct and I haven't forgot anything it should build without any problems.