Re: [PATCH v5] selftest: size: Add size test for Linux kernel

On Wed, 2014-12-03 at 08:29 -0800, Tim Bird wrote:

On 12/02/2014 07:43 PM, Michael Ellerman wrote:

quoted

On Tue, 2014-12-02 at 19:36 -0800, Tim Bird wrote:

quoted

This test shows the amount of memory used by the system.
Note that this is dependent on the user-space that is loaded
when this program runs.  Optimally, this program would be
run as the init program itself.

Sorry to only chime in at v5.

quoted

diff --git a/tools/testing/selftests/size/Makefile b/tools/testing/selftests/size/Makefile
new file mode 100644
index 0000000..47f8e9c
--- /dev/null
+++ b/tools/testing/selftests/size/Makefile

@@ -0,0 +1,15 @@
+#ifndef CC
+	CC = $(CROSS_COMPILE)gcc
+#endif

I think the following is preferable:

  CC := $(CROSS_COMPILE)$(CC)


It allows optionally setting a custom CC, as well as optionally CROSS_COMPILE.

I'm not sure I follow this.

If CC is unset, you get only the CROSS_COMPILE prefix.

CC is never unset. The default value is 'cc'.

If CC is set to e.g. 'gcc', then you get a nicely formatted toolchain string.

Right.

But if CC already has the prefix applied, then this will result in
  having it duplicated, which surely won't work correctly.

That's just PEBKAC. Don't specify CROSS_COMPILE and also a fully specified CC.
Try it with the kernel Makefile and see how well it works.

CROSS_COMPILE prefix usage looks a bit uncoordinated in the tools directory, but most
tests seem to be favoring $(CROSS_COMPILE)gcc.

That doesn't make it right :)

 $ cd tools ; mgrep CROSS

...

./testing/selftests/powerpc/Makefile:CC := $(CROSS_COMPILE)$(CC)

You can run git blame on that one if you like ;)

I agree it's desirable not to hardcode gcc, but we seem to be doing it all over
the place already.

If everyone jumped off a bridge ... :)

cheers