x86/efi: move the logic to detect PE build support

So that it can be used by other components apart from the efi specific
code. By moving the detection code creating a dummy efi/disabled file
can be avoided.

This is required so that the conditional used to define the efi symbol
in the linker script can be removed and instead the definition of the
efi symbol can be guarded using the preprocessor.

The motivation behind this change is to be able to build Xen using lld
(the LLVM linker), that at least on version 6.0.0 doesn't work
properly with a DEFINED being used in a conditional expression:

ld    -melf_x86_64_fbsd  -T xen.lds -N prelink.o --build-id=sha1 \
    /root/src/xen/xen/common/symbols-dummy.o -o /root/src/xen/xen/.xen-syms.0
ld: error: xen.lds:233: symbol not found: efi

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Daniel Kiper <daniel.kiper@oracle.com>

diff --git a/.gitignore b/.gitignore
index 55b78008c03969d2b0a379e57eecc1f71867843a..1625a8f0e7f4a38315fd9455dd52f587dda69305 100644 (file)
--- a/.gitignore
+++ b/.gitignore
@@ -302,7 +302,6 @@ xen/arch/x86/boot/*.bin
 xen/arch/x86/boot/*.lnk
 xen/arch/x86/efi.lds
 xen/arch/x86/efi/check.efi
-xen/arch/x86/efi/disabled
 xen/arch/x86/efi/mkreloc
 xen/arch/*/efi/boot.c
 xen/arch/*/efi/compat.c

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 5563c813dd71f3b037e14454a33190c95b8fd191..172685fb41ecb609193ca7785e13e768103a1aba 100644 (file)
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -163,10 +163,15 @@ EFI_LDFLAGS += --minor-image-version=$(XEN_SUBVERSION)
 EFI_LDFLAGS += --major-os-version=2 --minor-os-version=0
 EFI_LDFLAGS += --major-subsystem-version=2 --minor-subsystem-version=0
 
+# Check if the build system supports PE.
+XEN_BUILD_PE := $(shell $(CC) $(filter-out $(CFLAGS-y) .%.d,$(CFLAGS)) -c efi/check.c -o efi/check.o 2>/dev/null && echo y)
+export XEN_BUILD_PE := $(if $(XEN_BUILD_PE),$(shell $(LD) -mi386pep --subsystem=10 -o efi/check.efi efi/check.o 2>/dev/null && echo y))
+CFLAGS-$(XEN_BUILD_PE) += -DXEN_BUILD_PE
+
 $(TARGET).efi: VIRT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A VIRT_START$$,,p')
 $(TARGET).efi: ALT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A ALT_START$$,,p')
 # Don't use $(wildcard ...) here - at least make 3.80 expands this too early!
-$(TARGET).efi: guard = $(if $(shell echo efi/dis* | grep disabled),:)
+$(TARGET).efi: guard = $(if $(filter y,$(XEN_BUILD_PE)),,:)
 
 ifneq ($(build_id_linker),)
 ifeq ($(call ld-ver-build-id,$(LD) $(filter -m%,$(EFI_LDFLAGS))),y)
@@ -232,6 +237,6 @@ efi/mkreloc: efi/mkreloc.c
 clean::
        rm -f asm-offsets.s *.lds boot/*.o boot/*~ boot/core boot/mkelf32
        rm -f $(BASEDIR)/.xen-syms.[0-9]* boot/.*.d
-       rm -f $(BASEDIR)/.xen.efi.[0-9]* efi/*.efi efi/disabled efi/mkreloc
+       rm -f $(BASEDIR)/.xen.efi.[0-9]* efi/*.efi efi/mkreloc
        rm -f boot/cmdline.S boot/reloc.S boot/*.lnk boot/*.bin
        rm -f note.o

diff --git a/xen/arch/x86/efi/Makefile b/xen/arch/x86/efi/Makefile
index 3be96611089f35b06078461efccf0f4da225269e..918383b3256142de9ba66f5a91b1c28405452595 100644 (file)
--- a/xen/arch/x86/efi/Makefile
+++ b/xen/arch/x86/efi/Makefile
@@ -1,16 +1,11 @@
 CFLAGS += -fshort-wchar
 
-efi := y$(shell rm -f disabled)
-efi := $(if $(efi),$(shell $(CC) $(filter-out $(CFLAGS-y) .%.d,$(CFLAGS)) -c check.c 2>disabled && echo y))
-efi := $(if $(efi),$(shell $(LD) -mi386pep --subsystem=10 -o check.efi check.o 2>disabled && echo y))
-efi := $(if $(efi),$(shell rm disabled)y)
-
 %.o: %.ihex
        $(OBJCOPY) -I ihex -O binary $< $@
 
 boot.init.o: buildid.o
 
 obj-y := stub.o
-obj-$(efi) := boot.init.o compat.o relocs-dummy.o runtime.o
-extra-$(efi) += buildid.o
-nocov-$(efi) += stub.o
+obj-$(XEN_BUILD_PE) := boot.init.o compat.o relocs-dummy.o runtime.o
+extra-$(XEN_BUILD_PE) += buildid.o
+nocov-$(XEN_BUILD_PE) += stub.o

diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 326e885402abd9374709ad9367f7e8a8cc7d0f49..4a594679867d566819d49e81b6d5fd5d1ac364ce 100644 (file)
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -304,7 +304,9 @@ SECTIONS
   } :text
 #endif
 
-  efi = DEFINED(efi) ? efi : .;
+#ifndef XEN_BUILD_PE
+  efi = .;
+#endif
 
   /* Sections to be discarded */
   /DISCARD/ : {