[xen master] x86/EFI: don't insert timestamp when SOURCE_DATE_EPOCH is defined

[patchbot@xxxxxxx]

commit ee41b5c450032ae7f2531e18cd0a73bf5fb48803
Author:     Maximilian Engelhardt <maxi@xxxxxxxxxxxxx>
AuthorDate: Tue Dec 22 08:59:14 2020 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Dec 22 08:59:14 2020 +0100

    x86/EFI: don't insert timestamp when SOURCE_DATE_EPOCH is defined
    
    By default a timestamp gets added to the xen efi binary. Unfortunately
    ld doesn't seem to provide a way to set a custom date, like from
    SOURCE_DATE_EPOCH, so set a zero value for the timestamp (option
    --no-insert-timestamp) if SOURCE_DATE_EPOCH is defined. This makes
    reproducible builds possible.
    
    This is an alternative to the patch suggested in [1]. This patch only
    omits the timestamp when SOURCE_DATE_EPOCH is defined.
    
    [1] 
https://lists.xenproject.org/archives/html/xen-devel/2020-10/msg02161.html
    
    Signed-off-by: Maximilian Engelhardt <maxi@xxxxxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/Makefile | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 8f2180485b..863aed043f 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -184,6 +184,12 @@ EFI_LDFLAGS += --major-image-version=$(XEN_VERSION)
 EFI_LDFLAGS += --minor-image-version=$(XEN_SUBVERSION)
 EFI_LDFLAGS += --major-os-version=2 --minor-os-version=0
 EFI_LDFLAGS += --major-subsystem-version=2 --minor-subsystem-version=0
+# It seems ld unfortunately can't set a custom timestamp, so add a zero value
+# for the timestamp (option --no-insert-timestamp) if SOURCE_DATE_EPOCH is
+# defined to make reproducible builds possible.
+ifdef SOURCE_DATE_EPOCH
+EFI_LDFLAGS += --no-insert-timestamp
+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')
--
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