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>
master commit: 18cd4997d26b9df95dda87503e41c823279a07a0
master date: 2018-07-31 10:24:22 +0200

diff --git a/.gitignore b/.gitignore
index d6e0844b2ff49e3e561c1f982aa948c94693cf97..5e82f5807f89199139ceee6237219033788a5a2f 100644 (file)
--- a/.gitignore
+++ b/.gitignore
@@ -279,7 +279,6 @@ 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 1ecf4baeb6f6f9794fe411bd300510d574657c7f..54ba8137ee78b287d421ac3c4e8971edcfabfcc0 100644 (file)
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -159,10 +159,15 @@ 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)
@@ -224,6 +229,6 @@ 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 3edff1cf24cd96ce39e4a18568ec683ac6224450..6adce38e50e16041f4850cec5370a4ca04b66557 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
-nogcov-$(efi) += stub.o
+obj-$(XEN_BUILD_PE) := boot.init.o compat.o relocs-dummy.o runtime.o
+extra-$(XEN_BUILD_PE) += buildid.o
+nogcov-$(XEN_BUILD_PE) += stub.o

diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 48673c46aac4db63e633d3be018a158ad43e3eb6..a9722615ca011b5097b6346eba3d5354bc19dafa 100644 (file)
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -279,7 +279,9 @@ SECTIONS
   } :text
 #endif
 
-  efi = DEFINED(efi) ? efi : .;
+#ifndef XEN_BUILD_PE
+  efi = .;
+#endif
 
   /* Sections to be discarded */
   /DISCARD/ : {