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Re: make: .exe handling breaks kernel cross-compile


On 2012-06-10 13:29, Christopher Faylor wrote:
On Sun, Jun 10, 2012 at 01:06:18PM -0500, Yaakov (Cygwin/X) wrote:
I can confirm that this previously reported bug in make .exe handling
still affects the cross-compile of the Linux kernel:

http://cygwin.com/ml/cygwin/2009-11/msg00935.html

Without diving into the depths of the linux makefiles, this doesn't seem like a bug. gcc creates .exe files. The makefile isn't expecting to create one and, so, gets confused. Makefiles which expect .exe extensions usually use the EXEEXT variable for just this purpose. Linux's makefile doesn't do that for probably obvious reasons.

While our make won't connect a dep on "foo" to a foo.exe rule (which can occur in automake-generated Makefiles with custom rules), it does see foo.exe fulfilling a dep on "foo" if it is already present:


$ cat Makefile
all: bar
bar: foo
	touch bar.exe
clean:
	rm -f bar.exe foo.exe

$ touch foo.exe
$ make
touch bar.exe
$ make clean
rm -f bar.exe foo.exe

The problem here is the kernel uses VPATH -- scripts/pnmtologo(.exe) is not relative to drivers/video/logo, but rather to $(O) -- and somehow with VPATH the .exe magic doesn't happen:

$ cat Makefile
VPATH = $(PWD)/build

all: bar
bar: foo
	touch bar.exe

$ mkdir -p build
$ touch build/foo.exe
$ make
make: *** No rule to make target `foo', needed by `bar'.  Stop.

So foo.exe fulfills foo, but not with VPATH. Isn't that a bug?


Yaakov


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