Re: Kbuild Makefile output

Re: Kbuild Makefile output

[Sam Ravnborg]

On Thu, May 15, 2008 at 11:07:19PM +0530, murtuja bharmal wrote:
> Hello All.
> I want to collect all my object file in onedirectory and then want to create a kernel module.
> For example: This my directory structure.
> dir
> |
> --------------------------------------
> |            |        |        |
> dir1    dir2       dir3   dir4
> This is my makefile in 'dir'.
> obj-m := test.o
> test-objs += \
>                 dir1/test1.o  \
>                 dir2/test2.o  \
>                 dir3/test3.o
> all:
>             make -C /usr/src/linux M=`pwd` modules
> 
> Now I want to save all output objectfile test1.o test2.o test3.o in one directory
> called 'dir4' not in source directory. 'test.o' should look all this object file in 'dir4' for linking, not in the source directory and 'test.ko' should also be create in 'dir4'.
> Can any one tell me, what is require changes in Kernel Makefile for the same.

Do not do that...

If you really need to do so - please explain why so we can understand the rationale.
There are ~2000 modules that does not need this so what makes your maodule so special?

[Added kbuild@vger to cc as you also asked there]

	Sam

Re: Kbuild Makefile output

[murtuja bharmal]

Hello Sam,

Thanks for reply.
Actually Problem is.
As I told you I have near near about 1000 file that
compiles for single module creation which spread in
multiple directies in 2.4 with lots of makefile.

Now I have created single makefile to compile all this
file and able to create kernel module.

But now the problem is lots of file included in kernel
module, compiled twice or even more then twice for
user space (whithou kernel flag set) and kernel space
and this userspace binary is not a part of kbuild
makefile.

Previously in 2.4 we use to put all output object file
in different directories for kernel module and user
binaries based in their compilation Flags.

Now after attaching kbuild makefile with this system,
kbuild make all object file in source directory itself
becasue of that userspace makefiles not able to
compile those file again. Because one object file is
already there by kbuild. So I am not able create
userspace binary.

Now either solution is generate kbuild object file in
different directory not in source directory as per our
previous design or make a copy of exsisting file with
some other name. One for kernel and one for user
space.

So I thought lets check the possibility of generating
all kernel related object file in some other directory
not in source directory.


Thanks 
Murtuja

--- Sam Ravnborg <sam@ravnborg.org> wrote:

> On Thu, May 15, 2008 at 11:07:19PM +0530, murtuja
> bharmal wrote:
> > Hello All.
> > I want to collect all my object file in
> onedirectory and then want to create a kernel
> module.
> > For example: This my directory structure.
> > dir
> > |
> > --------------------------------------
> > |            |        |        |
> > dir1    dir2       dir3   dir4
> > This is my makefile in 'dir'.
> > obj-m := test.o
> > test-objs += \
> >                 dir1/test1.o  \
> >                 dir2/test2.o  \
> >                 dir3/test3.o
> > all:
> >             make -C /usr/src/linux M=`pwd` modules
> > 
> > Now I want to save all output objectfile test1.o
> test2.o test3.o in one directory
> > called 'dir4' not in source directory. 'test.o'
> should look all this object file in 'dir4' for
> linking, not in the source directory and 'test.ko'
> should also be create in 'dir4'.
> > Can any one tell me, what is require changes in
> Kernel Makefile for the same.
> 
> Do not do that...
> 
> If you really need to do so - please explain why so
> we can understand the rationale.
> There are ~2000 modules that does not need this so
> what makes your maodule so special?
> 
> [Added kbuild@vger to cc as you also asked there]
> 
> 	Sam
> 



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Re: Kbuild Makefile output

[murtuja bharmal]

--- Sam Ravnborg <sam@ravnborg.org> wrote:

> On Thu, May 15, 2008 at 11:07:19PM +0530, murtuja
> bharmal wrote:
> > Hello All.
> > I want to collect all my object file in
> onedirectory and then want to create a kernel
> module.
> > For example: This my directory structure.
> > dir
> > |
> > --------------------------------------
> > |            |        |        |
> > dir1    dir2       dir3   dir4
> > This is my makefile in 'dir'.
> > obj-m := test.o
> > test-objs += \
> >                 dir1/test1.o  \
> >                 dir2/test2.o  \
> >                 dir3/test3.o
> > all:
> >             make -C /usr/src/linux M=`pwd` modules
> > 
> > Now I want to save all output objectfile test1.o
> test2.o test3.o in one directory
> > called 'dir4' not in source directory. 'test.o'
> should look all this object file in 'dir4' for
> linking, not in the source directory and 'test.ko'
> should also be create in 'dir4'.
> > Can any one tell me, what is require changes in
> Kernel Makefile for the same.
> 
> Do not do that...
> 
> If you really need to do so - please explain why so
> we can understand the rationale.
> There are ~2000 modules that does not need this so
> what makes your maodule so special?
> 
> [Added kbuild@vger to cc as you also asked there]
> 
> 	Sam
> 

Hello Sam,

Thanks for reply.
Actually Problem is.
As I told you I have near near about 1000 file that
compiles for single module creation which spread in
multiple directies in 2.4 with lots of makefile.

Now I have created single makefile to compile all this
file and able to create kernel module.

But now the problem is lots of file included in kernel
module, compiled twice or even more then twice for
user space (whithou kernel flag set) and kernel space
as well.

Previously in 2.4 we use to put all output object file
in different directories for kernel module and user
binaries based on their compilation Flags.

Now after attaching kbuild makefile with this system,
kbuild make all object file in source directory itself
becasue of that userspace makefiles not able to
compile those file again. Because one object file is
already there by kbuild. So I am not able create
userspace binary.

Now either solution is generate kbuild object file in
different directory not in source directory as per our
previous design or make a copy of exsisting file with
some other name. One for kernel and one for user
space but this is also not a good approach.

So I thought lets check the possibility of generating
all kernel related object file in some other directory
not in source directory.
So I just want to know whether it is possible or not
and if possible how.


Thanks 
Murtuja




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Re: Kbuild Makefile output

[Joel Becker]

On Thu, May 15, 2008 at 07:31:31PM +0100, murtuja bharmal wrote:
> But now the problem is lots of file included in kernel
> module, compiled twice or even more then twice for
> user space (whithou kernel flag set) and kernel space
> as well.
> 
> Previously in 2.4 we use to put all output object file
> in different directories for kernel module and user
> binaries based on their compilation Flags.
> 
> Now after attaching kbuild makefile with this system,
> kbuild make all object file in source directory itself
> becasue of that userspace makefiles not able to
> compile those file again. Because one object file is
> already there by kbuild. So I am not able create
> userspace binary.

Two solutions.

1) Have the build name the output files appropritately.  That is,
compile foo.c to foo-kernel.o and foo-userspace.o.  Then link as needed.
The makefile dependencies Just Work.

2) Better - create a kbuild symlink farm.  That is, lay out your sources
however you want, but in a single directory that is not the parent put
your kbuild makefile.  Have it symlink all .c files for kernel building
into this directory.

toplevel
	dir1
		Makefile
		foo.c
	dir2
		Makefile
		bar.c
	dir3
		Makefile
		baz.c
	kbuild
		Makefile

The kbuild/Makefile does something like:

obj-$(CONFIG_MYMODULE) += mymodule.o
mymodule-objs := foo.o bar.o baz.o
mymodule-sources = $(patsubst %.o,%.c,$(mymodule-objs))

obj-sources = $(foreach obj,$(mymodule-sources),$(wildcard ../*/$(obj)))

$(mymodule-sources): $(obj-sources)
	for f in $(obj-sources); do	\
	  -ln -s $$f .;			\
	done

Joel

-- 

Life's Little Instruction Book #232

	"Keep your promises."

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127

Re: Kbuild Makefile output

[murtuja bharmal]

--- Joel Becker <Joel.Becker@oracle.com> wrote:

> 1) Have the build name the output files
> appropritately.  That is,
> compile foo.c to foo-kernel.o and foo-userspace.o. 
> Then link as needed.
> The makefile dependencies Just Work.
> 

Thanks Joel,
In case of Solution 1.
what changes required in Makefile.
I mean how to build foo-kernel.c from foo.c using
kbuild makefile.

Suppose this is my makefile

obj-m := mymodule.o

mymodule-objs += \
         dir1/foo.o   \
         dir2/bar.o   

all:
         make -C /usr/src/linux M=`pwd` modules.

I only want to change name for foo.c to foo-kernel.o,
not for bar.c.

Thanks
Murtuja
 


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Re: Kbuild Makefile output

[Joel Becker]

On Fri, May 16, 2008 at 07:03:55AM +0100, murtuja bharmal wrote:
> 
> --- Joel Becker <Joel.Becker@oracle.com> wrote:
> 
> > 1) Have the build name the output files
> > appropritately.  That is,
> > compile foo.c to foo-kernel.o and foo-userspace.o. 
> > Then link as needed.
> > The makefile dependencies Just Work.
> > 
> 
> Thanks Joel,
> In case of Solution 1.
> what changes required in Makefile.
> I mean how to build foo-kernel.c from foo.c using
> kbuild makefile.

	I still prefer solution 2, but for solution 1, you could do
multiple things.  You could leave them as 
them foo.o and foo-userspace.o.  That is, build the kernel drivers
without a rename.  Whatever you do, you're going to hvae to be
consistent.  So...

> Suppose this is my makefile
> 
> obj-m := mymodule.o
> 
> mymodule-objs += \
>          dir1/foo.o   \
>          dir2/bar.o   
> 
> all:
>          make -C /usr/src/linux M=`pwd` modules.
> 
> I only want to change name for foo.c to foo-kernel.o,
> not for bar.c.

	Why would you do that?  bar.c is part of the kernel driver, so
it should be bar-kernel.o if you are renaming.  You don't have to
rename, of course.  You could use 'foo.o' for kernel objects and
'foo-userspace.o' for userspace objects.

Joel
-- 

"People with narrow minds usually have broad tongues."

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127

Re: Kbuild Makefile output

[murtuja bharmal]

> On Fri, May 16, 2008 at 07:03:55AM +0100, murtuja
> bharmal wrote:
> > 
> > --- Joel Becker <Joel.Becker@oracle.com> wrote:
> > 
> > > 1) Have the build name the output files
> > > appropritately.  That is,
> > > compile foo.c to foo-kernel.o and
> foo-userspace.o. 
> > > Then link as needed.
> > > The makefile dependencies Just Work.
> > > 
> > 
> > Thanks Joel,
> > In case of Solution 1.
> > what changes required in Makefile.
> > I mean how to build foo-kernel.c from foo.c using
> > kbuild makefile.
> 
> 	I still prefer solution 2, but for solution 1, you
> could do
> multiple things.  You could leave them as 
> them foo.o and foo-userspace.o.  That is, build the
> kernel drivers
> without a rename.  Whatever you do, you're going to
> hvae to be
> consistent.  So...
> 
> > Suppose this is my makefile
> > 
> > obj-m := mymodule.o
> > 
> > mymodule-objs += \
> >          dir1/foo.o   \
> >          dir2/bar.o   
> > 
> > all:
> >          make -C /usr/src/linux M=`pwd` modules.
> > 
> > I only want to change name for foo.c to
> foo-kernel.o,
> > not for bar.c.
> 
> 	Why would you do that?  bar.c is part of the kernel
> driver, so
> it should be bar-kernel.o if you are renaming.  You
> don't have to
> rename, of course.  You could use 'foo.o' for kernel
> objects and
> 'foo-userspace.o' for userspace objects.
> 

Actaually foo.c is common file for kernel space and
user space and bar.c is only a part of kernel space.
Anyway if we can change object file name for all
source file without changing source file name, then
also no issue but I just want to know whether it is
possible or not.

I tried to hard to find out way to put object file in
differnet directory not in source directory, to change
a name of individual object file or all object file,
other then source name.
But didn't find any clear idea in internet or kbuild
documentation.

I think in case of 2.4 lots things is possible because
we are using it as normal makefile.

Thanks 
Murtuja 


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Re: Kbuild Makefile output

[Joel Becker]

On Fri, May 16, 2008 at 12:36:30PM +0100, murtuja bharmal wrote:
> Actaually foo.c is common file for kernel space and
> user space and bar.c is only a part of kernel space.
> Anyway if we can change object file name for all
> source file without changing source file name, then
> also no issue but I just want to know whether it is
> possible or not.

	In general, kbuild wants to find a source file with the same
name as the object file.  That you can't change.  It also expects to
build object files in the same directory as their source files.  This is
why I suggested a special directory where you symlink all the required
sources for a kernel build, then let kbuild do the rest.
	To sum up - pick the names you want for the files in a kernel
build.  Set them in mymodule-objs.  Then if those names are different
than your actual source file, come up with a rule to change the name.

Joel

-- 

"It is not the function of our government to keep the citizen from
 falling into error; it is the function of the citizen to keep the
 government from falling into error."
	- Robert H. Jackson

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127