[PATCH v2 0/2] EFI build improvements

[PATCH v2 0/2] EFI build improvements

[Roger Pau Monne]

Hello,

The following patches started as a workaround to build Xen using lld
(the LLVM linker), but now patch #2 is an improvement of the build
system, thus allowing to create a multiboot2 capable ELF binary
requiring just a compiler that supports the MS ABI. Previously in order
to build a multiboot2 capable ELF binary linker PE support was also
required.

Thanks, Roger.

Roger Pau Monne (2):
  x86/efi: move the logic to detect PE build support
  x86/efi: split compiler vs linker support

 .gitignore                |  1 -
 xen/arch/x86/Makefile     | 12 ++++++++++--
 xen/arch/x86/efi/Makefile | 11 +++--------
 xen/arch/x86/xen.lds.S    |  4 +++-
 4 files changed, 16 insertions(+), 12 deletions(-)

-- 
2.17.1


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

[PATCH v2 1/2] x86/efi: move the logic to detect PE build support

[Roger Pau Monne]

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>
---
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
---
Changes since v1:
 - Rename variable.
 - Remove usage of the efi/disabled file.
---
 .gitignore                |  1 -
 xen/arch/x86/Makefile     | 11 +++++++++--
 xen/arch/x86/efi/Makefile | 11 +++--------
 xen/arch/x86/xen.lds.S    |  4 +++-
 4 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/.gitignore b/.gitignore
index 5b8448d8f7..aa6856c2b9 100644
--- 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 5563c813dd..2172a07071 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -163,10 +163,17 @@ 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 $(LD) -mi386pep --subsystem=10 -o efi/check.efi efi/check.o 2>/dev/null && echo y))
+ifeq ($(XEN_BUILD_PE),y)
+CFLAGS += -DXEN_BUILD_PE
+endif
+
 $(TARGET).efi: VIRT_BASE = 0x$(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 $(XEN_BUILD_PE),,:)
 
 ifneq ($(build_id_linker),)
 ifeq ($(call ld-ver-build-id,$(LD) $(filter -m%,$(EFI_LDFLAGS))),y)
@@ -232,6 +239,6 @@ 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 3be9661108..918383b325 100644
--- 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 326e885402..4a59467986 100644
--- 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/ : {
-- 
2.17.1


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

[PATCH v2 2/2] x86/efi: split compiler vs linker support

[Roger Pau Monne]

So that an ELF binary with support for EFI services will be built when
the compiler supports the MS ABI, regardless of the linker support for
PE.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
---
Changes since v1:
 - New in this version.
---
 xen/arch/x86/Makefile     | 11 ++++++-----
 xen/arch/x86/efi/Makefile |  6 +++---
 xen/arch/x86/xen.lds.S    |  2 +-
 3 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 2172a07071..7736d37d4c 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -163,11 +163,12 @@ 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 $(LD) -mi386pep --subsystem=10 -o efi/check.efi efi/check.o 2>/dev/null && echo y))
-ifeq ($(XEN_BUILD_PE),y)
-CFLAGS += -DXEN_BUILD_PE
+# Check if the compiler supports the MS ABI.
+export XEN_BUILD_EFI := $(shell $(CC) $(filter-out $(CFLAGS-y) .%.d,$(CFLAGS)) -c efi/check.c -o efi/check.o 2>/dev/null && echo y)
+# Check if the linker supports PE.
+XEN_BUILD_PE := $(if $(XEN_BUILD_EFI),$(shell $(LD) -mi386pep --subsystem=10 -o efi/check.efi efi/check.o 2>/dev/null && echo y))
+ifeq ($(XEN_BUILD_EFI),y)
+CFLAGS += -DXEN_BUILD_EFI
 endif
 
 $(TARGET).efi: VIRT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A VIRT_START$$,,p')
diff --git a/xen/arch/x86/efi/Makefile b/xen/arch/x86/efi/Makefile
index 918383b325..3816de2738 100644
--- a/xen/arch/x86/efi/Makefile
+++ b/xen/arch/x86/efi/Makefile
@@ -6,6 +6,6 @@ CFLAGS += -fshort-wchar
 boot.init.o: buildid.o
 
 obj-y := stub.o
-obj-$(XEN_BUILD_PE) := boot.init.o compat.o relocs-dummy.o runtime.o
-extra-$(XEN_BUILD_PE) += buildid.o
-nocov-$(XEN_BUILD_PE) += stub.o
+obj-$(XEN_BUILD_EFI) := boot.init.o compat.o relocs-dummy.o runtime.o
+extra-$(XEN_BUILD_EFI) += buildid.o
+nocov-$(XEN_BUILD_EFI) += stub.o
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 4a59467986..6e9bda5109 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -304,7 +304,7 @@ SECTIONS
   } :text
 #endif
 
-#ifndef XEN_BUILD_PE
+#ifndef XEN_BUILD_EFI
   efi = .;
 #endif
 
-- 
2.17.1


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

Re: [PATCH v2 1/2] x86/efi: move the logic to detect PE build support

[Jan Beulich]

>>> On 16.07.18 at 16:07, <roger.pau@citrix.com> wrote:
> --- a/xen/arch/x86/Makefile
> +++ b/xen/arch/x86/Makefile
> @@ -163,10 +163,17 @@ 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))

As said before I'm not overly happy with the movement here, but I guess
all other options are worse.

> +ifeq ($(XEN_BUILD_PE),y)
> +CFLAGS += -DXEN_BUILD_PE
> +endif

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 $(XEN_BUILD_PE),,:)

With this new approach the check going wrong could actually be overridden
by passing XEN_BUILD_PE= to make. Since in the "disable" case it would be
more natural to pass XEN_BUILD_PE=n, I'd prefer if the above became

$(TARGET).efi: guard = $(if $(filter y,$(XEN_BUILD_PE)),,:)

With these adjustments
Reviewed-by: Jan Beulich <jbeulich@suse.com>
but I'd prefer for Daniel to confirm that this isn't going to make his life
more complicated.

Jan



_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

Re: [PATCH v2 2/2] x86/efi: split compiler vs linker support

[Jan Beulich]

>>> On 16.07.18 at 16:07, <roger.pau@citrix.com> wrote:
> --- a/xen/arch/x86/Makefile
> +++ b/xen/arch/x86/Makefile
> @@ -163,11 +163,12 @@ 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 $(LD) -mi386pep --subsystem=10 -o efi/check.efi efi/check.o 2>/dev/null && echo y))
> -ifeq ($(XEN_BUILD_PE),y)
> -CFLAGS += -DXEN_BUILD_PE
> +# Check if the compiler supports the MS ABI.
> +export XEN_BUILD_EFI := $(shell $(CC) $(filter-out $(CFLAGS-y) .%.d,$(CFLAGS)) -c efi/check.c -o efi/check.o 2>/dev/null && echo y)
> +# Check if the linker supports PE.
> +XEN_BUILD_PE := $(if $(XEN_BUILD_EFI),$(shell $(LD) -mi386pep --subsystem=10 -o efi/check.efi efi/check.o 2>/dev/null && echo y))
> +ifeq ($(XEN_BUILD_EFI),y)
> +CFLAGS += -DXEN_BUILD_EFI
>  endif

With this suitably re-based according to the changes requested to
patch 1:
Reviewed-by: Jan Beulich <jbeulich@suse.com>


Jan



_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

Re: [PATCH v2 2/2] x86/efi: split compiler vs linker support

[Daniel Kiper]

On Wed, Jul 18, 2018 at 03:35:20AM -0600, Jan Beulich wrote:
> >>> On 16.07.18 at 16:07, <roger.pau@citrix.com> wrote:
> > --- a/xen/arch/x86/Makefile
> > +++ b/xen/arch/x86/Makefile
> > @@ -163,11 +163,12 @@ 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 $(LD) -mi386pep --subsystem=10 -o efi/check.efi efi/check.o 2>/dev/null && echo y))
> > -ifeq ($(XEN_BUILD_PE),y)
> > -CFLAGS += -DXEN_BUILD_PE
> > +# Check if the compiler supports the MS ABI.
> > +export XEN_BUILD_EFI := $(shell $(CC) $(filter-out $(CFLAGS-y) .%.d,$(CFLAGS)) -c efi/check.c -o efi/check.o 2>/dev/null && echo y)
> > +# Check if the linker supports PE.
> > +XEN_BUILD_PE := $(if $(XEN_BUILD_EFI),$(shell $(LD) -mi386pep --subsystem=10 -o efi/check.efi efi/check.o 2>/dev/null && echo y))
> > +ifeq ($(XEN_BUILD_EFI),y)
> > +CFLAGS += -DXEN_BUILD_EFI
> >  endif
>
> With this suitably re-based according to the changes requested to
> patch 1:
> Reviewed-by: Jan Beulich <jbeulich@suse.com>

Patches LGTM +/- Jan comments. Though I would like to test the
final version just to be sure. So, Roger, may I ask you to post
the patches which takes into account Jan's comments?

Daniel

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel