Embedded white space in out-of-tree module full pathname

Embedded white space in out-of-tree module full pathname

[Mason]

Hello,

I'd like some confirmation that this is either not supported, or that
I'm doing something obviously wrong. (Kernel 3.14 if it matters.)

Suppose the source code for an out-of-tree kernel module is stored e.g.
in "/tmp/foo bar/module" (note the embedded space in the path name)

Here is the Makefile template I'm using. (Maybe it's wrong.)

/tmp/foo bar/module$ cat Makefile
KDIR          ?= /home/mason/linux-3.14
ARCH          ?= arm
CROSS_COMPILE ?= arm-none-linux-gnueabi-

obj-m += mytest.o

all:
	make -C $(KDIR) M="$$PWD"

clean:
	make -C $(KDIR) M="$$PWD" clean

/tmp/foo bar/module$ make
make -C /home/mason/linux-3.14 M="$PWD"
make[1]: Entering directory `/home/mason/linux-3.14'
scripts/Makefile.build:44: /tmp/foo/Makefile: No such file or directory
make[2]: *** No rule to make target `/tmp/foo/Makefile'.  Stop.
make[1]: *** [_module_/tmp/foo] Error 2
make[1]: Leaving directory `/home/mason/linux-3.14'
make: *** [all] Error 2


Does the kernel build system support building an out-of-tree module whose
full pathname contains embedded white space, like in my example?

Do I have an obvious mistake in my Makefile?

Regards.

Re: Embedded white space in out-of-tree module full pathname

[Russell King - ARM Linux]

On Tue, Jan 27, 2015 at 10:44:41AM +0100, Mason wrote:
> I'd like some confirmation that this is either not supported, or that
> I'm doing something obviously wrong. (Kernel 3.14 if it matters.)

It's something which isn't going to be supported.

Various things in the make makes it difficult - for example:

module-dirs := $(addprefix _module_,$(KBUILD_EXTMOD))

and as per your example, addprefix will see "/tmp/foo" and "bar/module"
as two separate words.  make has no way to know that these are one
path rather than two separate paths.

See the addprefix documentation in make's info pages, which splits the
second argument by whitespace.

Unlike shell, where you have IFS= which can change the word splitting,
make always uses white space.

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