| Message ID | 20230727145447.2701-2-anthony.perard@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | build: reduce number of $(shell) execution on make 4.4 | expand |
On 27.07.2023 16:54, Anthony PERARD wrote: > With GNU make 4.4, the number of execution of the command present in > these $(shell ) increased greatly. This is probably because as of make > 4.4, exported variable are also added to the environment of $(shell ) > construct. > > Also, `make -d` shows a lot of these: > Makefile:15: not recursively expanding XEN_BUILD_DATE to export to shell function > Makefile:16: not recursively expanding XEN_BUILD_TIME to export to shell function > Makefile:17: not recursively expanding XEN_BUILD_HOST to export to shell function > Makefile:14: not recursively expanding XEN_DOMAIN to export to shell function > > So to avoid having these command been run more than necessary, we > will replace ?= by an equivalent but with immediate expansion. > > Reported-by: Jason Andryuk <jandryuk@gmail.com> > Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com>
diff --git a/xen/Makefile b/xen/Makefile index e8aa663781..c1738dbbde 100644 --- a/xen/Makefile +++ b/xen/Makefile @@ -11,10 +11,18 @@ export XEN_FULLVERSION = $(XEN_VERSION).$(XEN_SUBVERSION)$(XEN_EXTRAVERSION) -include xen-version export XEN_WHOAMI ?= $(USER) -export XEN_DOMAIN ?= $(shell ([ -x /bin/dnsdomainname ] && /bin/dnsdomainname) || ([ -x /bin/domainname ] && /bin/domainname || echo [unknown])) -export XEN_BUILD_DATE ?= $(shell LC_ALL=C date) -export XEN_BUILD_TIME ?= $(shell LC_ALL=C date +%T) -export XEN_BUILD_HOST ?= $(shell hostname) +ifeq ($(origin XEN_DOMAIN), undefined) +export XEN_DOMAIN := $(shell ([ -x /bin/dnsdomainname ] && /bin/dnsdomainname) || ([ -x /bin/domainname ] && /bin/domainname || echo [unknown])) +endif +ifeq ($(origin XEN_BUILD_DATE), undefined) +export XEN_BUILD_DATE := $(shell LC_ALL=C date) +endif +ifeq ($(origin XEN_BUILD_TIME), undefined) +export XEN_BUILD_TIME := $(shell LC_ALL=C date +%T) +endif +ifeq ($(origin XEN_BUILD_HOST), undefined) +export XEN_BUILD_HOST := $(shell hostname) +endif # Best effort attempt to find a python interpreter, defaulting to Python 3 if # available. Fall back to just `python` if `which` is nowhere to be found.
With GNU make 4.4, the number of execution of the command present in these $(shell ) increased greatly. This is probably because as of make 4.4, exported variable are also added to the environment of $(shell ) construct. Also, `make -d` shows a lot of these: Makefile:15: not recursively expanding XEN_BUILD_DATE to export to shell function Makefile:16: not recursively expanding XEN_BUILD_TIME to export to shell function Makefile:17: not recursively expanding XEN_BUILD_HOST to export to shell function Makefile:14: not recursively expanding XEN_DOMAIN to export to shell function So to avoid having these command been run more than necessary, we will replace ?= by an equivalent but with immediate expansion. Reported-by: Jason Andryuk <jandryuk@gmail.com> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> --- Notes: v3: - replace evaluation on first use construct by immediate expansion which isn't likely to break and is clearer. xen/Makefile | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)