28/06/2017 16:07, Luca Boccassi: > On Tue, 2017-06-27 at 18:14 +0200, Thomas Monjalon wrote: > > 27/06/2017 16:51, Luca Boccassi: > > > On Tue, 2017-06-27 at 15:52 +0200, Thomas Monjalon wrote: > > > > 27/06/2017 12:43, Luca Boccassi: > > > > > On Tue, 2017-06-27 at 01:20 +0200, Thomas Monjalon wrote: > > > > > > 23/06/2017 20:41, lbocc...@brocade.com: > > > > > > > From: Luca Boccassi <luca.bocca...@gmail.com> > > > > > > > > > > > > > > In order to achieve reproducible builds, always use the > > > > > > > same > > > > > > > order when listing object files to build dependencies > > > > > > > lists. > > > > > > > > > > > > > > Signed-off-by: Luca Boccassi <luca.bocca...@gmail.com> > > > > > > > --- > > > > > > > mk/rte.app.mk | 4 ++-- > > > > > > > mk/rte.hostapp.mk | 4 ++-- > > > > > > > mk/rte.shared.mk | 4 ++-- > > > > > > > 3 files changed, 6 insertions(+), 6 deletions(-) > > > > > > > > > > > > > > --- a/mk/rte.app.mk > > > > > > > +++ b/mk/rte.app.mk > > > > > > > @@ -263,8 +263,8 @@ LDLIBS_NAMES += $(patsubst -Wl$(comma)- > > > > > > > l%,lib%.a,$(filter -Wl$(comma)-l%,$(LDLIB > > > > > > > > > > > > > > # list of found libraries files (useful for deps). If not > > > > > > > found, > > > > > > > the > > > > > > > # library is silently ignored and dep won't be checked > > > > > > > -LDLIBS_FILES := $(wildcard $(foreach dir,$(LDLIBS_PATH),\ > > > > > > > - $(addprefix $(dir)/,$(LDLIBS_NAMES)))) > > > > > > > +LDLIBS_FILES := $(sort $(wildcard $(foreach > > > > > > > dir,$(LDLIBS_PATH),\ > > > > > > > + $(addprefix $(dir)/,$(LDLIBS_NAMES))))) > > > > > > > > > > > > You cannot sort libraries. > > > > > > Check - for instance - this comment above in this file: > > > > > > # Eliminate duplicates without sorting, only keep the > > > > > > last > > > > > > occurrence > > > > > > filter-libs = \ > > > > > > > > > > Not sure I follow - what's the reason for avoiding to sort the > > > > > list > > > > > of > > > > > libs to link against? > > > > > > > > Sorry, the ordering issue is with LDLIBS not LDLIBS_FILES. > > > > > > > > > > Why sorting them? > > > > > > What is random in libraries list? > > > > > > > > > > The issue is that the output of wildcard is not fully > > > > > deterministic. It > > > > > can depend on the filesystem, and even on the locale settings > > > > > [1]. > > > > > Before GNU Make 3.82 (2009) it used to automatically sort the > > > > > output, > > > > > but that was removed (to make it faster... sigh). [2] > > > > > > > > It is not a true wildcard here. It is just filtering files which > > > > do not exist. > > > > I think you do not need this patch for deterministic build. > > > > > > But then those lists are passed down in the .SECONDEXPANSION rule > > > right? > > > > I do not follow you. > > Please explain what is the benefit of the patch in the next version. > > I thought that these lists are used to determine which files to > recompile - and incidentally, in which order as they are passed in this > snippet in rte.compile-pre.mk: > > .SECONDEXPANSION: > %.o: %.c $$(wildcard $$(dep_$$@)) $$(DEP_$$(@)) FORCE > @[ -d $(dir $@) ] || mkdir -p $(dir $@) > $(if $(D),\ > @echo -n "$< -> $@ " ; \ > echo -n "file_missing=$(call boolean,$(file_missing)) " ; \ > echo -n "cmdline_changed=$(call boolean,$(call > cmdline_changed,$(C_TO_O))) " ; \ > echo -n "depfile_missing=$(call boolean,$(depfile_missing)) " ; > \ > echo "depfile_newer=$(call boolean,$(depfile_newer))") > $(if $(or \ > $(file_missing),\ > $(call cmdline_changed,$(C_TO_O)),\ > $(depfile_missing),\ > $(depfile_newer)),\ > $(C_TO_O_DO)) > > Did I get that wrong? (It is a bit convoluted :-P )
LDLIBS_FILES are just used to link the executable AFAIK. The libraries are built in separate recursive make calls. > But nevertheless, I've finally found the root cause for the "wandering > header" - when building the libraries, CFLAGS lists > -I$(RTE_OUTDIR)/include first and then -I$(SRCDIR) last. There is a > race, and sometimes when GCC is called the public header has already > been installed in RTE_OUTDIR and sometimes it has not. This causes the > instability, and causes the expansion of __FILE__ and the directory > listing in the DWARF objects to randomly list the full path to either > RTE_OUTDIR/include or SRCDIR for each library. > > By always passing -I$(SRCDIR) first this instability is solved. Good news.
