Honour the O= flag that was passed to a higher level Makefile and then passed
down as part of a tool build.
To make this work, the top-level Makefile passes the original O= flag and
subdir=tools to the tools/Makefile, and that in turn passes
subdir=$(O)/$(subdir)/foodir when building tool foo in directory
$(O)/$(subdir)/foodir (where the intervening slashes aren't added if an
element is missing).
For example, take perf. This is found in tools/perf/. Assume we're building
into directory ~/zebra/, so we pass O=~/zebra to make. Dependening on where
we run the build from, we see:
make run in dir $(OUTPUT) dir
======================= ==================
linux ~/zebra/tools/perf/
linux/tools ~/zebra/perf/
linux/tools/perf ~/zebra/
and if O= is not set, we get:
make run in dir $(OUTPUT) dir
======================= ==================
linux linux/tools/perf/
linux/tools linux/tools/perf/
linux/tools/perf linux/tools/perf/
The output directories are created by the descend function if they don't
already exist.
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Borislav Petkov <bp@amd64.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1378.1352379110@warthog.procyon.org.uk
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When I did a compile of perf using a relative path for the output
directory, the build failed when it tried to compile libtraceevent. This
is because it continues to use the same relative path when the new
working directory is in a different path.
SUBDIR ../lib/traceevent/
/bin/sh: line 0: cd: ../../../nobackup/perf/: No such file or directory
Makefile:74: *** output directory "../../../nobackup/perf/" does not exist. Stop.
make: *** [../../../nobackup/perf///libtraceevent.a] Error 2
Make the path used an absolute path when building perf with O=.
Boris:
Teach Makefile to check whether the supplied O= directory exists and
bail out if not. Reportedly, kernel dudes are idiots and need to be
guarded so as not to shoot themselves in the foot when playing in the
sandbox.
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120815163923.GD15989@aftab.osrc.amd.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
