--- /dev/null
+From f3f431a712729a1af94d01bd1bfde17a252ff02c Mon Sep 17 00:00:00 2001
+From: Paul Kocialkowski <contact@paulk.fr>
+Date: Sun, 26 Jul 2015 18:48:15 +0200
+Subject: [PATCH] Reproducible U-Boot build support, using SOURCE_DATE_EPOCH
+
+In order to achieve reproducible builds in U-Boot, timestamps that are defined
+at build-time have to be somewhat eliminated. The SOURCE_DATE_EPOCH environment
+variable allows setting a fixed value for those timestamps.
+
+Simply by setting SOURCE_DATE_EPOCH to a fixed value, a number of targets can be
+built reproducibly. This is the case for e.g. sunxi devices.
+
+However, some other devices might need some more tweaks, especially regarding
+the image generation tools.
+
+Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
+---
+ Makefile | 7 ++++---
+ README | 12 ++++++++++++
+ tools/default_image.c | 21 ++++++++++++++++++++-
+ 3 files changed, 36 insertions(+), 4 deletions(-)
+
+--- a/README
++++ b/README
+@@ -2785,6 +2785,18 @@ Low Level (hardware related) configurati
+ that is executed before the actual U-Boot. E.g. when
+ compiling a NAND SPL.
+
++Reproducible builds
++-------------------
++
++In order to achieve reproducible builds, timestamps used in the U-Boot build
++process have to be set to a fixed value.
++
++This is done using the SOURCE_DATE_EPOCH environment variable.
++SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
++option for U-Boot or an environment variable in U-Boot.
++
++SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
++
+ Building the Software:
+ ======================
+
+--- a/tools/default_image.c
++++ b/tools/default_image.c
+@@ -101,6 +101,9 @@ static void image_set_header (void *ptr,
+ struct mkimage_params *params)
+ {
+ uint32_t checksum;
++ char *source_date_epoch;
++ struct tm *time_universal;
++ time_t time;
+
+ image_header_t * hdr = (image_header_t *)ptr;
+
+@@ -109,9 +112,25 @@ static void image_set_header (void *ptr,
+ sizeof(image_header_t)),
+ sbuf->st_size - sizeof(image_header_t));
+
++source_date_epoch = getenv("SOURCE_DATE_EPOCH");
++ if (source_date_epoch != NULL) {
++ time = (time_t) strtol(source_date_epoch, NULL, 10);
++
++ time_universal = gmtime(&time);
++ if (time_universal == NULL) {
++ fprintf(stderr, "%s: SOURCE_DATE_EPOCH is not valid\n",
++ __func__);
++ time = 0;
++ } else {
++ time = mktime(time_universal);
++ }
++ } else {
++ time = sbuf->st_mtime;
++ }
++
+ /* Build new header */
+ image_set_magic (hdr, IH_MAGIC);
+- image_set_time (hdr, sbuf->st_mtime);
++ image_set_time(hdr, time);
+ image_set_size (hdr, sbuf->st_size - sizeof(image_header_t));
+ image_set_load (hdr, params->addr);
+ image_set_ep (hdr, params->ep);
--- /dev/null
+--- a/Makefile
++++ b/Makefile
+@@ -389,8 +389,26 @@ $(VERSION_FILE):
+ @cmp -s $@ $@.tmp && rm -f $@.tmp || mv -f $@.tmp $@
+
+ $(TIMESTAMP_FILE):
+- @date +'#define U_BOOT_DATE "%b %d %C%y"' > $@
+- @date +'#define U_BOOT_TIME "%T"' >> $@
++ (if test -n "$${SOURCE_DATE_EPOCH}"; then \
++ SOURCE_DATE="@$${SOURCE_DATE_EPOCH}"; \
++ DATE=""; \
++ for date in gdate date.gnu date; do \
++ $${date} -u -d "$${SOURCE_DATE}" >/dev/null 2>&1 && DATE="$${date}"; \
++ done; \
++ if test -n "$${DATE}"; then \
++ LC_ALL=C $${DATE} -u -d "$${SOURCE_DATE}" +'#define U_BOOT_DATE "%b %d %C%y"' > $@; \
++ LC_ALL=C $${DATE} -u -d "$${SOURCE_DATE}" +'#define U_BOOT_TIME "%T"' >> $@; \
++ LC_ALL=C $${DATE} -u -d "$${SOURCE_DATE}" +'#define U_BOOT_TZ "%z"' >> $@; \
++ LC_ALL=C $${DATE} -u -d "$${SOURCE_DATE}" +'#define U_BOOT_DMI_DATE "%m/%d/%Y"' >> $@; \
++ else \
++ return 42; \
++ fi; \
++ else \
++ LC_ALL=C date +'#define U_BOOT_DATE "%b %d %C%y"'; \
++ LC_ALL=C date +'#define U_BOOT_TIME "%T"'; \
++ LC_ALL=C date +'#define U_BOOT_TZ "%z"'; \
++ LC_ALL=C date +'#define U_BOOT_DMI_DATE "%m/%d/%Y"'; \
++ fi)
+
+ gdbtools:
+ $(MAKE) -C tools/gdb all || exit 1
-diff -ur u-boot-2010.03/cpu/mips/Makefile u-boot-nbg/cpu/mips/Makefile
---- u-boot-2010.03/cpu/mips/Makefile 2010-03-31 23:54:39.000000000 +0200
-+++ u-boot-nbg/cpu/mips/Makefile 2010-04-15 18:58:01.000000000 +0200
-@@ -33,6 +33,7 @@
+--- a/cpu/mips/Makefile
++++ b/cpu/mips/Makefile
+@@ -33,6 +33,7 @@ SOBJS-$(CONFIG_INCA_IP) += incaip_wdt.o
COBJS-$(CONFIG_INCA_IP) += asc_serial.o incaip_clock.o
COBJS-$(CONFIG_PURPLE) += asc_serial.o
COBJS-$(CONFIG_SOC_AU1X00) += au1x00_eth.o au1x00_serial.o au1x00_usb_ohci.o
SRCS := $(START:.o=.S) $(SOBJS-y:.o=.S) $(COBJS-y:.o=.c)
OBJS := $(addprefix $(obj),$(SOBJS-y) $(COBJS-y))
-diff -ur u-boot-2010.03/Makefile u-boot-nbg/Makefile
---- u-boot-2010.03/Makefile 2010-03-31 23:54:39.000000000 +0200
-+++ u-boot-nbg/Makefile 2010-04-11 23:31:29.000000000 +0200
-@@ -3455,6 +3455,13 @@
+--- a/Makefile
++++ b/Makefile
+@@ -3474,6 +3474,13 @@ qemu_mips_config : unconfig
@$(MKCONFIG) -a qemu-mips mips mips qemu-mips
#########################################################################