From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Anthony PERARD <anthony.perard@citrix.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Julien Grall <julien@xen.org>, Wei Liu <wl@xen.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
George Dunlap <George.Dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Ian Jackson <ian.jackson@eu.citrix.com>,
Jan Beulich <jbeulich@suse.com>,
xen-devel@lists.xenproject.org,
Daniel De Graaf <dgdegra@tycho.nsa.gov>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Subject: Re: [Xen-devel] [XEN PATCH v3 15/23] xen/build: have the root Makefile generates the CFLAGS
Date: Thu, 27 Feb 2020 12:05:04 +0100 [thread overview]
Message-ID: <20200227110504.GN24458@Air-de-Roger.citrite.net> (raw)
In-Reply-To: <20200226113355.2532224-16-anthony.perard@citrix.com>
On Wed, Feb 26, 2020 at 11:33:47AM +0000, Anthony PERARD wrote:
> Instead of generating the CFLAGS in Rules.mk everytime we enter a new
> subdirectory, we are going to generate most of them a single time, and
> export the result in the environment so that Rules.mk can use it. The
> only flags left to generates are the one that depends on the targets,
^ be generated ^ ones ^ depend
I think (albeit I'm not a native speaker).
> but the variable $(c_flags) takes care of that.
>
> Arch specific CFLAGS are generated by a new file "arch/*/arch.mk"
> which is included by the root Makefile.
>
> We export the *FLAGS via the environment variables XEN_*FLAGS because
> Rules.mk still includes Config.mk and would add duplicated flags to
> CFLAGS.
>
> When running Rules.mk in the root directory (xen/), the variable
> `root-make-done' is set, so `need-config' will remain undef and so the
> root Makefile will not generate the cflags again.
>
> We can't use CFLAGS in subdirectories to add flags to particular
> targets, instead start to use CFLAGS-y. Idem for AFLAGS.
> So there are two different CFLAGS-y, the one in xen/Makefile (and
> arch.mk), and the one in subdirs that Rules.mk is going to use.
> We can't add to XEN_CFLAGS because it is exported, so making change to
> it might be propagated to subdirectory which isn't intended.
>
> Some style change are introduced in this patch:
> when LDFLAGS_DIRECT is included in LDFLAGS
> use of CFLAGS-$(CONFIG_INDIRECT_THUNK) instead of ifeq().
>
> There is on FIXME added about LTO build, but since LTO is marked as
> BROKEN, this commit doesn't attempt to filter -flto flags out of the
> CFLAGS.
>
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> ---
>
> Notes:
> v3:
> - squash "xen/build: introduce ccflags-y and CFLAGS_$@" here, with
> those changes:
> - rename ccflags-y to simply CFLAGS-y and start using AFLAGS-y in
> subdirs.
> - remove CFLAGS_$@, we don't need it yet.
> - fix build of xen.lds and efi.lds which needed -D to be a_flags
> - remove arch_ccflags, and modify c_flags directly
> with that change, reorder c_flags, so that target specific flags are last.
> - remove HAVE_AS_QUOTED_SYM from envvar and check XEN_CFLAGS to find if
> it's there when adding -D__OBJECT_LABEL__.
> - fix missing some flags in AFLAGS
> (like -fshort-wchar in xen/arch/x86/efi/Makefile,
> and -D__OBJECT_LABEL__ and CFLAGS-stack-boundary)
> - keep COV_FLAGS generation in Rules.mk since it doesn't invovle to
> call CC
> - fix clang test for "asm()-s support .include." (in a new patch done
> ahead)
> - include Kconfig.include in xen/Makefile because as-option-add is
> defined there now.
>
> xen/Makefile | 60 ++++++++++++++++++++++++
> xen/Rules.mk | 74 ++++++++----------------------
> xen/arch/arm/Makefile | 10 ++--
> xen/arch/arm/Rules.mk | 93 --------------------------------------
> xen/arch/arm/arch.mk | 88 ++++++++++++++++++++++++++++++++++++
> xen/arch/arm/efi/Makefile | 2 +-
> xen/arch/x86/Makefile | 24 +++++-----
> xen/arch/x86/Rules.mk | 91 +++----------------------------------
> xen/arch/x86/arch.mk | 84 ++++++++++++++++++++++++++++++++++
> xen/arch/x86/efi/Makefile | 2 +-
> xen/common/libelf/Makefile | 4 +-
> xen/common/libfdt/Makefile | 4 +-
> xen/include/Makefile | 2 +-
> xen/xsm/flask/Makefile | 2 +-
> xen/xsm/flask/ss/Makefile | 2 +-
> 15 files changed, 283 insertions(+), 259 deletions(-)
> create mode 100644 xen/arch/arm/arch.mk
> create mode 100644 xen/arch/x86/arch.mk
>
> diff --git a/xen/Makefile b/xen/Makefile
> index a6120e577e9b..da017dc29d36 100644
> --- a/xen/Makefile
> +++ b/xen/Makefile
> @@ -94,6 +94,8 @@ config: FORCE
>
> else # !config-build
>
> +include scripts/Kbuild.include
> +
> ifeq ($(need-config),y)
> include include/config/auto.conf
> # Read in dependencies to all Kconfig* files, make sure to run syncconfig if
> @@ -113,6 +115,64 @@ $(KCONFIG_CONFIG):
> include/config/%.conf include/config/%.conf.cmd: $(KCONFIG_CONFIG)
> $(MAKE) -f $(BASEDIR)/tools/kconfig/Makefile.kconfig ARCH=$(ARCH) SRCARCH=$(SRCARCH) HOSTCC="$(HOSTCC)" HOSTCXX="$(HOSTCXX)" syncconfig
>
> +ifeq ($(CONFIG_DEBUG),y)
> +CFLAGS += -O1
> +else
> +CFLAGS += -O2
> +endif
Long term we might want to make the optimization level selectable in
Kconfig IMO.
> +
> +ifeq ($(CONFIG_FRAME_POINTER),y)
> +CFLAGS += -fno-omit-frame-pointer
> +else
> +CFLAGS += -fomit-frame-pointer
> +endif
> +
> +CFLAGS += -nostdinc -fno-builtin -fno-common
> +CFLAGS += -Werror -Wredundant-decls -Wno-pointer-arith
> +$(call cc-option-add,CFLAGS,CC,-Wvla)
> +CFLAGS += -pipe -D__XEN__ -include $(BASEDIR)/include/xen/config.h
> +CFLAGS-$(CONFIG_DEBUG_INFO) += -g
> +
> +ifneq ($(CONFIG_CC_IS_CLANG),y)
> +# Clang doesn't understand this command line argument, and doesn't appear to
> +# have an suitable alternative. The resulting compiled binary does function,
^ a
> +# but has an excessively large symbol table.
> +CFLAGS += -Wa,--strip-local-absolute
This is not really related to clang, but to the assembler. If clang is
used with -no-integrated-as it's quite likely that the GNU assembler
will be used, and hence this option would be available.
Can we use cc-option-add here in order to detect whether the build
toolchain support the option?
Ideally this should be done after the integrated assembler tests
performed in x86/Rules.mk.
> +endif
> +
> +AFLAGS += -D__ASSEMBLY__
> +
> +CFLAGS += $(CFLAGS-y)
> +# allow extra CFLAGS externally via EXTRA_CFLAGS_XEN_CORE
> +CFLAGS += $(EXTRA_CFLAGS_XEN_CORE)
> +
> +# Most CFLAGS are safe for assembly files:
> +# -std=gnu{89,99} gets confused by #-prefixed end-of-line comments
> +# -flto makes no sense and annoys clang
> +AFLAGS += $(filter-out -std=gnu% -flto,$(CFLAGS))
> +
> +# LDFLAGS are only passed directly to $(LD)
> +LDFLAGS += $(LDFLAGS_DIRECT) $(LDFLAGS-y)
> +
> +ifeq ($(CONFIG_UBSAN),y)
> +CFLAGS_UBSAN := -fsanitize=undefined
> +else
> +CFLAGS_UBSAN :=
Do you need to define this to empty so it can be exported below? Isn't
it enough to just not set it at all?
> +endif
> +
> +ifeq ($(CONFIG_LTO),y)
> +CFLAGS += -flto
> +LDFLAGS-$(CONFIG_CC_IS_CLANG) += -plugin LLVMgold.so
> +endif
> +
> +include $(BASEDIR)/arch/$(TARGET_ARCH)/arch.mk
The strip-local-absolute check should be done after this AFAICT.
> +
> +# define new variables to avoid the ones defines in Config.mk
> +export XEN_CFLAGS := $(CFLAGS)
> +export XEN_AFLAGS := $(AFLAGS)
> +export XEN_LDFLAGS := $(LDFLAGS)
> +export CFLAGS_UBSAN
You might want to rename this to XEN_CFLAGS_UBSAN for coherency with
the rest of the exported variables?
Thanks, Roger.
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next prev parent reply other threads:[~2020-02-27 11:05 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-26 11:33 [Xen-devel] [XEN PATCH v3 00/23] xen: Build system improvements Anthony PERARD
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 01/23] xen/include: remove include of Config.mk Anthony PERARD
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 02/23] Makefile: Fix install-tests Anthony PERARD
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 03/23] xen/build: Remove confusing comment on the %.s:%.S rule Anthony PERARD
2020-02-26 11:53 ` Wei Liu
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 04/23] xen/build: remove use of AFLAGS-y Anthony PERARD
2020-02-26 12:58 ` Jan Beulich
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 05/23] xen/build: Allow to test clang .include without asm symlink Anthony PERARD
2020-02-27 9:05 ` Roger Pau Monné
2020-02-27 9:22 ` Jan Beulich
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 06/23] xen/build: Fix section-renaming of libfdt and libelf Anthony PERARD
2020-02-27 9:38 ` Jan Beulich
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 07/23] xen/build: Use obj-y += subdir/ instead of subdir-y Anthony PERARD
2020-02-27 9:22 ` Roger Pau Monné
2020-02-27 9:43 ` Jan Beulich
2020-03-04 14:14 ` Jan Beulich
2020-03-05 9:24 ` Jan Beulich
2020-03-05 13:42 ` Andrew Cooper
2020-03-05 15:02 ` Julien Grall
2020-03-05 15:59 ` Anthony PERARD
2020-03-05 16:31 ` Julien Grall
2020-03-09 6:46 ` Tian, Kevin
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 08/23] xen/build: use $(clean) shorthand for clean targets Anthony PERARD
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 09/23] xen/build: extract clean target from Rules.mk Anthony PERARD
2020-03-04 14:13 ` Jan Beulich
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 10/23] xen/build: run targets csopes, tags, .. without Rules.mk Anthony PERARD
2020-03-04 14:17 ` Jan Beulich
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 11/23] xen/build: make tests in test/ directly Anthony PERARD
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 12/23] xen/build: Move as-option-add to xen/ Anthony PERARD
2020-03-04 14:17 ` Jan Beulich
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 13/23] xen/build: include include/config/auto.conf in main Makefile Anthony PERARD
2020-03-04 14:29 ` Jan Beulich
2020-03-10 17:10 ` Anthony PERARD
2020-03-11 9:26 ` Jan Beulich
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 14/23] xen/build: use new $(c_flags) and $(a_flags) instead of $(CFLAGS) Anthony PERARD
2020-02-27 10:22 ` Roger Pau Monné
2020-03-10 17:55 ` Anthony PERARD
2020-03-04 14:42 ` Jan Beulich
2020-03-10 17:43 ` Anthony PERARD
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 15/23] xen/build: have the root Makefile generates the CFLAGS Anthony PERARD
2020-02-27 11:05 ` Roger Pau Monné [this message]
2020-03-17 18:05 ` Anthony PERARD
2020-03-19 16:24 ` Anthony PERARD
2020-03-23 15:11 ` Roger Pau Monné
2020-03-24 17:11 ` [Xen-devel] " Anthony PERARD
2020-03-04 15:00 ` Jan Beulich
2020-03-17 18:35 ` Anthony PERARD
2020-03-18 10:20 ` Jan Beulich
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 16/23] xen/build: introduce if_changed and if_changed_rule Anthony PERARD
2020-03-04 15:45 ` Jan Beulich
2020-03-18 10:44 ` Anthony PERARD
2020-03-18 11:14 ` Jan Beulich
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 17/23] xen/build: Start using if_changed Anthony PERARD
2020-02-27 13:09 ` Roger Pau Monné
2020-03-04 16:00 ` Jan Beulich
2020-03-18 10:52 ` Anthony PERARD
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 18/23] xen/build: use if_changed on built_in.o Anthony PERARD
2020-03-04 16:03 ` Jan Beulich
2020-03-18 10:55 ` Anthony PERARD
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 19/23] xen/build: Use if_changed_rules with %.o:%.c targets Anthony PERARD
2020-03-04 16:09 ` Jan Beulich
2020-03-18 11:14 ` Anthony PERARD
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 20/23] xen/build: factorise generation of the linker scripts Anthony PERARD
2020-02-27 13:14 ` Roger Pau Monné
2020-03-05 11:07 ` Jan Beulich
2020-03-05 11:05 ` Jan Beulich
2020-03-18 11:59 ` Anthony PERARD
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 21/23] xen/build: Use if_changed for prelink*.o Anthony PERARD
2020-02-27 13:16 ` Roger Pau Monné
2020-03-04 16:12 ` Jan Beulich
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 22/23] xen, symbols: rework file symbols selection Anthony PERARD
2020-03-05 14:44 ` Jan Beulich
2020-02-26 11:33 ` [Xen-devel] [XEN PATCH v3 23/23] xen/build: use if_changed to build guest_%.o Anthony PERARD
2020-03-05 15:12 ` Jan Beulich
2020-02-27 21:17 ` [Xen-devel] [XEN PATCH v3 00/23] xen: Build system improvements Stewart Hildebrand
2020-03-06 10:12 ` Anthony PERARD
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