Re: make -C tools clean failure on older systems

[Shuah Khan <shuahkh@osg.samsung.com>]

On 05/14/2015 09:54 AM, Arnaldo Carvalho de Melo wrote:
> Em Thu, May 14, 2015 at 09:39:43AM -0600, Shuah Khan escreveu:
>> On 05/14/2015 09:12 AM, Arnaldo Carvalho de Melo wrote:
>>> Hi,
>>>
>>> 	In:
>>>
>>>  -------------
>>> commit 67d8712dcc70aa16d8e14a52eb73870e3cbddfc2
>>> Author: Shuah Khan <shuahkh@osg.samsung.com>
>>> Date:   Wed Mar 18 11:57:39 2015 -0600
>>>
>>>     selftests: Fix build failures when invoked from kselftest target
>>>
>>>  -------------
>>>
>>> You cleaned two variables using different methods, any reason for that?
>>>
>>> I asked because the 'undefine' method causes it to fail in older
>>> systems:
>>
>> The reason for this change is some tests fail to build when invoked
>> from the main Makefile level. The commit log explains the change:
> 
> I saw it
> 
>>> +++ b/tools/testing/selftests/Makefile
>>> @@ -27,7 +27,7 @@ TARGETS_HOTPLUG += memory-hotplug
>>>  # Makefile to avoid test build failures when test
>>>  # Makefile doesn't have explicit build rules.
>>>  ifeq (1,$(MAKELEVEL))
>>> -undefine LDFLAGS
>>> +override LDFLAGS =
>>>  override MAKEFLAGS =
>>>  endif
>>
>> I recall testing with override and remember it to not work. If you would
> 
> bummer, then its not that easy, I thought it was an oversight, but if
> you tested it and it didn't work, nevermind, no need, I guess, to
> support older systems if it requires more, non trivial, work.
> 
>> like experiment with it, feel free to send a patch with that change. My
>> make version is very new:
>>
>> make --version
>> GNU Make 4.0
>> Built for x86_64-pc-linux-gnu
>>
>> You have to run make kselftest from the main kernel Makefile to see
>> the build failures that undefine LDFLAGS fixed.
>>

Hmm. I ran a quick test with override and it worked. My recollection
must not be good. :) Here is what I tried:

diff --git a/tools/testing/selftests/Makefile
b/tools/testing/selftests/Makefile
index ebac6b8..56b11cd 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -28,7 +28,7 @@ TARGETS_HOTPLUG += memory-hotplug
 # Makefile to avoid test build failures when test
 # Makefile doesn't have explicit build rules.
 ifeq (1,$(MAKELEVEL))
-undefine LDFLAGS
+override LDFLAGS =
 override MAKEFLAGS =
 endif


Could you please try this and let me know if it works and if
you have time, please send me a patch as well.

thanks,
-- Shuah

-- 
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America (Silicon Valley)
shuahkh@osg.samsung.com | (970) 217-8978