[PATCH] tools: Use builtin $(abspath ...) instead of $(shell cd ... && pwd)

[PATCH] tools: Use builtin $(abspath ...) instead of $(shell cd ... && pwd)

[Thierry Reding]

From: Thierry Reding <treding@nvidia.com>

Avoid forking off a shell to resolve the absolute path of the output
directory when make's builtin $(abspath ...) function will do an
adequate job.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 Makefile                       | 4 ++--
 tools/scripts/Makefile.include | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index 173437debc87..c1e3ece3684f 100644
--- a/Makefile
+++ b/Makefile
@@ -1542,11 +1542,11 @@ image_name:
 # Clear a bunch of variables before executing the submake
 tools/: FORCE
 	$(Q)mkdir -p $(objtree)/tools
-	$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(filter --j% -j,$(MAKEFLAGS))" O=$(shell cd $(objtree) && /bin/pwd) subdir=tools -C $(src)/tools/
+	$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(src)/tools/
 
 tools/%: FORCE
 	$(Q)mkdir -p $(objtree)/tools
-	$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(filter --j% -j,$(MAKEFLAGS))" O=$(shell cd $(objtree) && /bin/pwd) subdir=tools -C $(src)/tools/ $*
+	$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(src)/tools/ $*
 
 # Single targets
 # ---------------------------------------------------------------------------
diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
index 5467da41dc72..4d34d0729ac9 100644
--- a/tools/scripts/Makefile.include
+++ b/tools/scripts/Makefile.include
@@ -1,7 +1,7 @@
 ifneq ($(O),)
 ifeq ($(origin O), command line)
 	dummy := $(if $(shell test -d $(O) || echo $(O)),$(error O=$(O) does not exist),)
-	ABSOLUTE_O := $(shell cd $(O) ; pwd)
+	ABSOLUTE_O := $(abspath $(O))
 	OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/)
 	COMMAND_O := O=$(ABSOLUTE_O)
 ifeq ($(objtree),)
-- 
2.8.0

Re: [PATCH] tools: Use builtin $(abspath ...) instead of $(shell cd ... && pwd)

[Michal Marek]

On 2016-04-08 11:15, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> Avoid forking off a shell to resolve the absolute path of the output
> directory when make's builtin $(abspath ...) function will do an
> adequate job.

The abspath function is not available in make 3.80.

Michal

Re: [PATCH] tools: Use builtin $(abspath ...) instead of $(shell cd ... && pwd)

[Thierry Reding]

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On Mon, Apr 18, 2016 at 04:46:53PM +0200, Michal Marek wrote:
> On 2016-04-08 11:15, Thierry Reding wrote:
> > From: Thierry Reding <treding@nvidia.com>
> > 
> > Avoid forking off a shell to resolve the absolute path of the output
> > directory when make's builtin $(abspath ...) function will do an
> > adequate job.
> 
> The abspath function is not available in make 3.80.

Do we really support make 3.80? It was released in 2002 and 3.81
followed in April 2006. That makes it a decade old now. I'd be surprised
if anyone was still using it to build recent kernels.

Is there a formal process for increasing the dependencies listed in
Documentation/Changes? Should I simply make that change as part of this
patch? Do we need broad approval?

Thierry

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Re: [PATCH] tools: Use builtin $(abspath ...) instead of $(shell cd ... && pwd)

[Maciej W. Rozycki]

On Mon, 18 Apr 2016, Thierry Reding wrote:

> > > Avoid forking off a shell to resolve the absolute path of the output
> > > directory when make's builtin $(abspath ...) function will do an
> > > adequate job.
> > 
> > The abspath function is not available in make 3.80.
> 
> Do we really support make 3.80? It was released in 2002 and 3.81
> followed in April 2006. That makes it a decade old now. I'd be surprised
> if anyone was still using it to build recent kernels.
> 
> Is there a formal process for increasing the dependencies listed in
> Documentation/Changes? Should I simply make that change as part of this
> patch? Do we need broad approval?

 Hmm, what problem are you trying to solve here?  Your proposal looks to 
me like a gratuitous requirement for users to upgrade their tool (its age 
doesn't matter), which is often a burden and in any case requires extra 
time which could be used for something else.  Don't fix what ain't broke!

  Maciej

Re: [PATCH] tools: Use builtin $(abspath ...) instead of $(shell cd ... && pwd)

[Thierry Reding]

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On Mon, Apr 18, 2016 at 04:17:26PM +0100, Maciej W. Rozycki wrote:
> On Mon, 18 Apr 2016, Thierry Reding wrote:
> 
> > > > Avoid forking off a shell to resolve the absolute path of the output
> > > > directory when make's builtin $(abspath ...) function will do an
> > > > adequate job.
> > > 
> > > The abspath function is not available in make 3.80.
> > 
> > Do we really support make 3.80? It was released in 2002 and 3.81
> > followed in April 2006. That makes it a decade old now. I'd be surprised
> > if anyone was still using it to build recent kernels.
> > 
> > Is there a formal process for increasing the dependencies listed in
> > Documentation/Changes? Should I simply make that change as part of this
> > patch? Do we need broad approval?
> 
>  Hmm, what problem are you trying to solve here?  Your proposal looks to 
> me like a gratuitous requirement for users to upgrade their tool (its age 
> doesn't matter), which is often a burden and in any case requires extra 
> time which could be used for something else.  Don't fix what ain't broke!

Fine.

Thierry

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Re: [PATCH] tools: Use builtin $(abspath ...) instead of $(shell cd ... && pwd)

[Masahiro Yamada]

Hi Thierry,


2016-04-19 0:32 GMT+09:00 Thierry Reding <thierry.reding@gmail.com>:
> On Mon, Apr 18, 2016 at 04:17:26PM +0100, Maciej W. Rozycki wrote:
>> On Mon, 18 Apr 2016, Thierry Reding wrote:
>>
>> > > > Avoid forking off a shell to resolve the absolute path of the output
>> > > > directory when make's builtin $(abspath ...) function will do an
>> > > > adequate job.
>> > >
>> > > The abspath function is not available in make 3.80.
>> >
>> > Do we really support make 3.80? It was released in 2002 and 3.81
>> > followed in April 2006. That makes it a decade old now. I'd be surprised
>> > if anyone was still using it to build recent kernels.
>> >
>> > Is there a formal process for increasing the dependencies listed in
>> > Documentation/Changes? Should I simply make that change as part of this
>> > patch? Do we need broad approval?
>>
>>  Hmm, what problem are you trying to solve here?  Your proposal looks to
>> me like a gratuitous requirement for users to upgrade their tool (its age
>> doesn't matter), which is often a burden and in any case requires extra
>> time which could be used for something else.  Don't fix what ain't broke!
>
> Fine.
>
> Thierry


Are you still interested in this patch?

Actually, Kbuild had not been working with GNU Make 3.80
before you submitted this patch.
(In other words, Kbuild had already depended on GNU Make 3.81)


Now Kbuild _officially_ depends on GNU Make 3.81
(commit 37d69ee30808), so I think your patch is acceptable
and $(abspath ...) looks cleaner to me.
This patch no longer applies, so you need to rebase it, though.

-- 
Best Regards
Masahiro Yamada