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xen/Config.mk
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Ian Jackson d6b12add90 DEPS handling: Remove absolute paths from references to cwd 
In some directories we use gcc on source files elsewhere, to generate
a .o here in the current directory.  Eg in tools/libxl/,
   gcc -I -o build.o /path/to/libacpi/build.c
We pass -MMD and -MF options to generate a .d file right here.

In the general case this .c file might need to include things from the
directory here, eg libacpi/build.c eventually #includes various
*libxl*.h.  We pass gcc -I. for this, which means things from the cwd
where we invoked gcc, not the directory of the #including file.

When we do this, gcc's -MMD output mentions /path/to/libxl/*libxl*.h,
even though it could refer to simply *libxl*.h.  This is presumably
because gcc has noticed that `.' in this context must mean relative to
the invocation cwd, not relative to build.c, and gcc doesn't realise
that references in the .d file are also wrt the invocation cwd.

make distinguishes targets purely textually.  It will canonicalise a
target name by removing ./ before comparison (so _libxl_types.h and
./_libxl_types.h are considered the same target) but it won't examine
the filesystem.  So _libxl_types.h and
/path/to/tools/libxl/_libxl_types.h are different targets.

And, _libxl_types.h is generated from a pattern rule.  This pattern
rule is therefore instatiated twice, and the two instances may be run
concurrently - but use the same tempfiles and can therefore fail.

The thing that is wrong here is gcc's choice to output an absolute
path.

We could work around it by adding a rule to teach make about a
relationship between these `two different files'.  But this has to be
done for every autogenerated file and is therefore fragile (leaving a
race bug when we get it wrong).

Ideally we would fix the problem by fixing the .d file as it is
generated.  But the .d files are generated by many many rules
mentioning $(CC) and $(CFLAGS).  (We might in theory pass a bash
process substitution to -MF, but 1. that's not portable to people who
don't have bash and 2. it hangs, anyway.)

So instead we do this conversion at include time.  That is, we tell
make to include not the raw .d files, but the sedded ones.

The sedding removes occurrences of ` $PWD/'.  We use the shell
variable PWD because the make variable sometimes refers to the xen
toplevel.  If gcc's output format should change, then this sed rune
may not work any more, but that doesn't seem very likely.

The rune is only effective for dependencies on files which are exactly
in the current directory, or a subdirectory of it named simply by its
subdirectory name.  If there are autogenerated include files which
exist in a sibling (or worse, somewhere completely else), this
approach will not work, because we'd have to figure out what name this
Makefile usually uses to refer to them.  Hopefully such things don't
exist.

The indirect variables DEPS_RM and DEPS_INCLUDE are necessary to
preserve the assumptions made in the various Makefiles.  Specifically,
xen/ Makefiles assume that it is ok to say DEPS+=something (where
something is in a subdirectory); tools/ Makefiles all used to include
DEPS themselves (but now they include DEPS_INCLUDE); and many
Makefiles tended to explictly rm DEPS (but now rm DEPS_RM).

In the new scheme of things: DEPS is the files that come out of gcc
(or perhaps an assembler or something) and may be assigned to by
Makefiles.  DEPS_INCLUDE is the processed form.  And DEPS_RM is both
combined, so that they both get cleaned.

We need to explicitly use $(wildcard ) to do the wildcard expansion on
DEPS a bit earlier.  If we didn't, then DEPS_INCLUDE would contain
`.*.d2' which would not exist.

Evaluation order: DEPS_RM and DEPS_INCLUDE are recursively expanded
variables, so that although they are defined early (in Config.mk),
their actual values are computed at the time of use, using the value
of DEPS that is prevailing at that time.

Reported-by: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
2017-09-07 16:22:05 +01:00

307 lines
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Makefile
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# -*- mode: Makefile; -*-
ifeq ($(filter /%,$(XEN_ROOT)),)
$(error XEN_ROOT must be absolute)
endif
# Convenient variables
comma := ,
squote := '
empty :=
space := $(empty) $(empty)
# fallback for older make
realpath = $(wildcard $(foreach file,$(1),$(shell cd -P $(dir $(file)) && echo "$$PWD/$(notdir $(file))")))
or = $(if $(strip $(1)),$(1),$(if $(strip $(2)),$(2),$(if $(strip $(3)),$(3),$(if $(strip $(4)),$(4)))))
-include $(XEN_ROOT)/.config
XEN_COMPILE_ARCH ?= $(shell uname -m | sed -e s/i.86/x86_32/ \
-e s/i86pc/x86_32/ -e s/amd64/x86_64/ \
-e s/armv7.*/arm32/ -e s/armv8.*/arm64/ \
-e s/aarch64/arm64/)
XEN_TARGET_ARCH ?= $(XEN_COMPILE_ARCH)
XEN_OS ?= $(shell uname -s)
CONFIG_$(XEN_OS) := y
SHELL ?= /bin/sh
# Tools to run on system hosting the build
HOSTCFLAGS = -Wall -Werror -Wstrict-prototypes -O2 -fomit-frame-pointer
HOSTCFLAGS += -fno-strict-aliasing
DISTDIR ?= $(XEN_ROOT)/dist
DESTDIR ?= /
# Allow phony attribute to be listed as dependency rather than fake target
.PHONY: .phony
# If we are not cross-compiling, default HOSTC{C/XX} to C{C/XX}
ifeq ($(XEN_TARGET_ARCH), $(XEN_COMPILE_ARCH))
HOSTCC ?= $(CC)
HOSTCXX ?= $(CXX)
endif
# Use Clang/LLVM instead of GCC?
clang ?= n
ifeq ($(clang),n)
gcc := y
HOSTCC ?= gcc
HOSTCXX ?= g++
else
gcc := n
HOSTCC ?= clang
HOSTCXX ?= clang++
endif
DEPS_INCLUDE = $(addsuffix .d2, $(basename $(wildcard $(DEPS))))
DEPS_RM = $(DEPS) $(DEPS_INCLUDE)
%.d2: %.d
sed "s! $$PWD/! !" $^ >$@.tmp && mv -f $@.tmp $@
include $(XEN_ROOT)/config/$(XEN_OS).mk
include $(XEN_ROOT)/config/$(XEN_TARGET_ARCH).mk
# arguments: variable, common path part, path to test, if yes, if no
define setvar_dir
ifndef $(1)
ifneq (,$(wildcard $(2)$(3)))
$(1) ?= $(2)$(4)
else
$(1) ?= $(2)$(5)
endif
endif
endef
ifneq ($(EXTRA_PREFIX),)
EXTRA_INCLUDES += $(EXTRA_PREFIX)/include
EXTRA_LIB += $(EXTRA_PREFIX)/lib
endif
PYTHON ?= python
PYTHON_PREFIX_ARG ?= --prefix="$(prefix)"
# The above requires that prefix contains *no spaces*. This variable is here
# to permit the user to set PYTHON_PREFIX_ARG to '' to workaround this bug:
# https://bugs.launchpad.net/ubuntu/+bug/362570
# cc-option: Check if compiler supports first option, else fall back to second.
#
# This is complicated by the fact that unrecognised -Wno-* options:
# (a) are ignored unless the compilation emits a warning; and
# (b) even then produce a warning rather than an error
# To handle this we do a test compile, passing the option-under-test, on a code
# fragment that will always produce a warning (integer assigned to pointer).
# We then grep for the option-under-test in the compiler's output, the presence
# of which would indicate an "unrecognized command-line option" warning/error.
#
# Usage: cflags-y += $(call cc-option,$(CC),-march=winchip-c6,-march=i586)
cc-option = $(shell if test -z "`echo 'void*p=1;' | \
$(1) $(2) -S -o /dev/null -x c - 2>&1 | grep -- $(2) -`"; \
then echo "$(2)"; else echo "$(3)"; fi ;)
# cc-option-add: Add an option to compilation flags, but only if supported.
# Usage: $(call cc-option-add CFLAGS,CC,-march=winchip-c6)
cc-option-add = $(eval $(call cc-option-add-closure,$(1),$(2),$(3)))
define cc-option-add-closure
ifneq ($$(call cc-option,$$($(2)),$(3),n),n)
$(1) += $(3)
endif
endef
cc-options-add = $(foreach o,$(3),$(call cc-option-add,$(1),$(2),$(o)))
# cc-ver: Check compiler against the version requirement. Return boolean 'y'/'n'.
# Usage: ifeq ($(call cc-ver,$(CC),ge,0x030400),y)
cc-ver = $(shell if [ $$((`$(1) -dumpversion | awk -F. \
'{ printf "0x%02x%02x%02x", $$1, $$2, $$3}'`)) -$(2) $$(($(3))) ]; \
then echo y; else echo n; fi ;)
# cc-ver-check: Check compiler is at least specified version, else fail.
# Usage: $(call cc-ver-check,CC,0x030400,"Require at least gcc-3.4")
cc-ver-check = $(eval $(call cc-ver-check-closure,$(1),$(2),$(3)))
define cc-ver-check-closure
ifeq ($$(call cc-ver,$$($(1)),ge,$(2)),n)
override $(1) = echo "*** FATAL BUILD ERROR: "$(3) >&2; exit 1;
cc-option := n
endif
endef
# cc-ifversion: Check compiler version and take branch accordingly
# Usage $(call cc-ifversion,lt,0x040700,string_if_y,string_if_n)
cc-ifversion = $(shell [ $(call cc-ver,$(CC),$(1),$(2)) = "y" ] \
&& echo $(3) || echo $(4))
# Require GCC v4.1+
check-$(gcc) = $(call cc-ver-check,CC,0x040100,"Xen requires at least gcc-4.1")
$(eval $(check-y))
ld-ver-build-id = $(shell $(1) --build-id 2>&1 | \
grep -q build-id && echo n || echo y)
export XEN_HAS_BUILD_ID ?= n
ifeq ($(call ld-ver-build-id,$(LD)),n)
build_id_linker :=
else
CFLAGS += -DBUILD_ID
export XEN_HAS_BUILD_ID=y
build_id_linker := --build-id=sha1
endif
ifndef XEN_HAS_CHECKPOLICY
CHECKPOLICY ?= checkpolicy
XEN_HAS_CHECKPOLICY := $(shell $(CHECKPOLICY) -h 2>&1 | grep -q xen && echo y || echo n)
export XEN_HAS_CHECKPOLICY
endif
# as-insn: Check whether assembler supports an instruction.
# Usage: cflags-y += $(call as-insn "insn",option-yes,option-no)
as-insn = $(if $(shell echo 'void _(void) { asm volatile ( $(2) ); }' \
| $(1) $(filter-out -M% %.d -include %/include/xen/config.h,$(AFLAGS)) \
-c -x c -o /dev/null - 2>&1),$(4),$(3))
# as-insn-check: Add an option to compilation flags, but only if insn is
# supported by assembler.
# Usage: $(call as-insn-check CFLAGS,CC,"nop",-DHAVE_GAS_NOP)
as-insn-check = $(eval $(call as-insn-check-closure,$(1),$(2),$(3),$(4)))
define as-insn-check-closure
ifeq ($$(call as-insn,$$($(2)),$(3),y,n),y)
$(1) += $(4)
endif
endef
define buildmakevars2shellvars
export PREFIX="$(prefix)"; \
export XEN_SCRIPT_DIR="$(XEN_SCRIPT_DIR)"; \
export XEN_ROOT="$(XEN_ROOT)"
endef
#
# Compare $(1) and $(2) and replace $(2) with $(1) if they differ
#
# Typically $(1) is a newly generated file and $(2) is the target file
# being regenerated. This prevents changing the timestamp of $(2) only
# due to being auto regenereated with the same contents.
define move-if-changed
if ! cmp -s $(1) $(2); then mv -f $(1) $(2); else rm -f $(1); fi
endef
BUILD_MAKE_VARS := sbindir bindir LIBEXEC LIBEXEC_BIN libdir SHAREDIR \
XENFIRMWAREDIR XEN_CONFIG_DIR XEN_SCRIPT_DIR XEN_LOCK_DIR \
XEN_RUN_DIR XEN_PAGING_DIR XEN_DUMP_DIR XEN_LOG_DIR \
XEN_LIB_DIR XEN_RUN_STORED
buildmakevars2file = $(eval $(call buildmakevars2file-closure,$(1)))
define buildmakevars2file-closure
$(1): .phony
rm -f $(1).tmp; \
$(foreach var, $(BUILD_MAKE_VARS), \
echo "$(var)=\"$($(var))\"" >>$(1).tmp;) \
$(call move-if-changed,$(1).tmp,$(1))
endef
buildmakevars2header = $(eval $(call buildmakevars2header-closure,$(1)))
define buildmakevars2header-closure
$(1): .phony
rm -f $(1).tmp; \
$(foreach var, $(BUILD_MAKE_VARS), \
echo "#define $(var) \"$($(var))\"" >>$(1).tmp;) \
$(call move-if-changed,$(1).tmp,$(1))
endef
CFLAGS += -fno-strict-aliasing
CFLAGS += -std=gnu99
CFLAGS += -Wall -Wstrict-prototypes
$(call cc-option-add,HOSTCFLAGS,HOSTCC,-Wdeclaration-after-statement)
$(call cc-option-add,CFLAGS,CC,-Wdeclaration-after-statement)
$(call cc-option-add,CFLAGS,CC,-Wno-unused-but-set-variable)
$(call cc-option-add,CFLAGS,CC,-Wno-unused-local-typedefs)
LDFLAGS += $(foreach i, $(EXTRA_LIB), -L$(i))
CFLAGS += $(foreach i, $(EXTRA_INCLUDES), -I$(i))
LDFLAGS += $(foreach i, $(PREPEND_LIB), -L$(i))
CFLAGS += $(foreach i, $(PREPEND_INCLUDES), -I$(i))
ifeq ($(XEN_TOOLS_RPATH),y)
LDFLAGS += -Wl,-rpath,$(libdir)
endif
APPEND_LDFLAGS += $(foreach i, $(APPEND_LIB), -L$(i))
APPEND_CFLAGS += $(foreach i, $(APPEND_INCLUDES), -I$(i))
EMBEDDED_EXTRA_CFLAGS := -nopie -fno-stack-protector -fno-stack-protector-all
EMBEDDED_EXTRA_CFLAGS += -fno-exceptions
XEN_EXTFILES_URL ?= http://xenbits.xen.org/xen-extfiles
# All the files at that location were downloaded from elsewhere on
# the internet. The original download URL is preserved as a comment
# near the place in the Xen Makefiles where the file is used.
# Where to look for inlined subtrees (for example, from a tarball)
QEMU_UPSTREAM_INTREE ?= $(XEN_ROOT)/tools/qemu-xen
QEMU_TRADITIONAL_INTREE ?= $(XEN_ROOT)/tools/qemu-xen-traditional
# Handle legacy options
ifneq (,$(SEABIOS_UPSTREAM_TAG))
SEABIOS_UPSTREAM_REVISION ?= $(SEABIOS_UPSTREAM_TAG)
endif
ifneq (,$(QEMU_REMOTE))
QEMU_TRADITIONAL_URL ?= $(QEMU_REMOTE)
endif
ifneq (,$(CONFIG_QEMU))
QEMU_TRADITIONAL_LOC ?= $(CONFIG_QEMU)
endif
ifneq (,$(QEMU_TAG))
QEMU_TRADITIONAL_REVISION ?= $(QEMU_TAG)
endif
ifeq ($(GIT_HTTP),y)
OVMF_UPSTREAM_URL ?= http://xenbits.xen.org/git-http/ovmf.git
QEMU_UPSTREAM_URL ?= http://xenbits.xen.org/git-http/qemu-xen.git
QEMU_TRADITIONAL_URL ?= http://xenbits.xen.org/git-http/qemu-xen-traditional.git
SEABIOS_UPSTREAM_URL ?= http://xenbits.xen.org/git-http/seabios.git
MINIOS_UPSTREAM_URL ?= http://xenbits.xen.org/git-http/mini-os.git
else
OVMF_UPSTREAM_URL ?= git://xenbits.xen.org/ovmf.git
QEMU_UPSTREAM_URL ?= git://xenbits.xen.org/qemu-xen.git
QEMU_TRADITIONAL_URL ?= git://xenbits.xen.org/qemu-xen-traditional.git
SEABIOS_UPSTREAM_URL ?= git://xenbits.xen.org/seabios.git
MINIOS_UPSTREAM_URL ?= git://xenbits.xen.org/mini-os.git
endif
OVMF_UPSTREAM_REVISION ?= 5920a9d16b1ab887c2858224316a98e961d71b05
QEMU_UPSTREAM_REVISION ?= master
MINIOS_UPSTREAM_REVISION ?= d991bdbc062248221511ecb795617c36b37e1d2e
# Wed Aug 9 13:15:48 2017 +0100
# lib/math.c: implement __udivmoddi4
SEABIOS_UPSTREAM_REVISION ?= rel-1.10.2
# Wed Jun 22 14:53:24 2016 +0800
# fw/msr_feature_control: add support to set MSR_IA32_FEATURE_CONTROL
ETHERBOOT_NICS ?= rtl8139 8086100e
QEMU_TRADITIONAL_REVISION ?= 8051789e982499050680a26febeada7467e18a8d
# Thu Mar 9 11:14:55 2017 +0000
# cirrus/vnc: zap drop bitblit support from console code.
# Specify which qemu-dm to use. This may be `ioemu' to use the old
# Mercurial in-tree version, or a local directory, or a git URL.
# QEMU_UPSTREAM_LOC ?= `pwd`/$(XEN_ROOT)/../qemu-xen.git
# Defaults for subtree locations
QEMU_TRADITIONAL_LOC ?= $(call or,$(wildcard $(QEMU_TRADITIONAL_INTREE)),\
$(QEMU_TRADITIONAL_URL))
QEMU_UPSTREAM_LOC ?= $(call or,$(wildcard $(QEMU_UPSTREAM_INTREE)),\
$(QEMU_UPSTREAM_URL))
# Short answer -- do not enable this unless you know what you are
# doing and are prepared for some pain.
CONFIG_TESTS ?= y
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