[PATCH 5/5] hvmloader: add knob for fixed VGABIOS date string

[Olaf Hering <olaf@aepfle.de>]

To allow reproducible builds of hvmloader introduce a make variable
VGABIOS_REL_DATE="dd Mon yyyy" to provide a fixed date string. Without
this change the hvmloader binary changes with every rebuild.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
---
 INSTALL                         | 1 +
 tools/firmware/vgabios/Makefile | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/INSTALL b/INSTALL
index 198cb9d..1b67c36 100644
--- a/INSTALL
+++ b/INSTALL
@@ -215,6 +215,7 @@ can be used to provide fixed timestamps in the expected format.
 XEN_BUILD_DATE=any
 XEN_BUILD_TIME=hh:mm:ss
 SMBIOS_REL_DATE=mm/dd/yyyy
+VGABIOS_REL_DATE="dd Mon yyyy"
 
 The following variables can be used to tweak some aspects of the
 hypervisor build.
diff --git a/tools/firmware/vgabios/Makefile b/tools/firmware/vgabios/Makefile
index 51d9e6e..3284812 100644
--- a/tools/firmware/vgabios/Makefile
+++ b/tools/firmware/vgabios/Makefile
@@ -5,10 +5,10 @@ BCC = bcc
 AS86 = as86
 
 RELEASE = `pwd | sed "s-.*/--"`
-RELDATE = `date '+%d %b %Y'`
+VGABIOS_REL_DATE ?= `date '+%d %b %Y'`
 RELVERS = `pwd | sed "s-.*/--" | sed "s/vgabios//" | sed "s/-//"`
 
-VGABIOS_DATE = "-DVGABIOS_DATE=\"$(RELDATE)\""
+VGABIOS_DATE = "-DVGABIOS_DATE=\"$(VGABIOS_REL_DATE)\""
 
 .PHONY: all
 all: bios cirrus-bios