RE: Ping: [PATCH] build: tweak variable exporting for make 3.82

[Paul Durrant <xadimgnik@xxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: 02 July 2020 08:45
> To: Paul Durrant <paul@xxxxxxx>
> Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>; 
> xen-devel@xxxxxxxxxxxxxxxxxxxx; Andrew Cooper
> <andrew.cooper3@xxxxxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxxxxx>; Ian 
> Jackson
> <ian.jackson@xxxxxxxxxx>; Julien Grall <julien@xxxxxxx>; Wei Liu 
> <wl@xxxxxxx>; Stefano Stabellini
> <sstabellini@xxxxxxxxxx>
> Subject: Ping: [PATCH] build: tweak variable exporting for make 3.82
> 
> On 29.06.2020 18:30, Anthony PERARD wrote:
> > On Fri, Jun 26, 2020 at 05:02:30PM +0200, Jan Beulich wrote:
> >> While I've been running into an issue here only because of an additional
> >> local change I'm carrying, to be able to override just the compiler in
> >> $(XEN_ROOT)/.config (rather than the whole tool chain), in
> >> config/StdGNU.mk:
> >>
> >> ifeq ($(filter-out default undefined,$(origin CC)),)
> >>
> >> I'd like to propose to nevertheless correct the underlying issue:
> >> Exporting an unset variable changes its origin from "undefined" to
> >> "file". This comes into effect because of our adding of -rR to
> >> MAKEFLAGS, which make 3.82 wrongly applies also upon re-invoking itself
> >> after having updated auto.conf{,.cmd}.
> >>
> >> Move the export statement past $(XEN_ROOT)/config/$(XEN_OS).mk inclusion
> >> such that the variables already have their designated values at that
> >> point, while retaining their initial origin up to the point they get
> >> defined.
> >>
> >> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> >>
> >> --- a/xen/Makefile
> >> +++ b/xen/Makefile
> >> @@ -17,8 +17,6 @@ export XEN_BUILD_HOST    ?= $(shell hostnam
> >>  PYTHON_INTERPRETER        := $(word 1,$(shell which python3 python 
> >> python2 2>/dev/null) python)
> >>  export PYTHON             ?= $(PYTHON_INTERPRETER)
> >>
> >> -export CC CXX LD
> >> -
> >>  export BASEDIR := $(CURDIR)
> >>  export XEN_ROOT := $(BASEDIR)/..
> >>
> >> @@ -42,6 +40,8 @@ export TARGET_ARCH     := $(shell echo $
> >>  # Allow someone to change their config file
> >>  export KCONFIG_CONFIG ?= .config
> >>
> >> +export CC CXX LD
> >> +
> >>  .PHONY: default
> >>  default: build
> >
> > That patch is fine and it is probably better to export a variable that
> > has a value rather than before the variable is set.
> >
> > Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> 
> Paul - thoughts either way as to 4.14? If not to go in now, I
> definitely intend to backport it. (And in fact I'm meanwhile
> considering to enter a make bug for the behavior, unless its
> behavior has changed in later versions.)
> 

I agree with Anthony's statement so I'm happy for this to go in 4.14.

Release-acked-by: Paul Durrant <paul@xxxxxxx>