--- a/tools/mkimage.c
+++ b/tools/mkimage.c
-@@ -24,6 +24,7 @@
+@@ -24,6 +24,7 @@ struct image_tool_params params = {
.arch = IH_ARCH_PPC,
.type = IH_TYPE_KERNEL,
.comp = IH_COMP_GZIP,
.dtc = MKIMAGE_DEFAULT_DTC_OPTIONS,
.imagename = "",
.imagename2 = "",
-@@ -168,6 +169,16 @@
+@@ -168,6 +169,16 @@ main (int argc, char **argv)
genimg_get_comp_id (*++argv)) < 0)
usage ();
goto NXTARG;
case 'D':
if (--argc <= 0)
usage ();
-@@ -623,12 +634,13 @@
+@@ -623,12 +634,13 @@ static void usage(void)
fprintf (stderr, "Usage: %s -l image\n"
" -l ==> list image header information\n",
params.cmdname);
" -n ==> set image name to 'name'\n"
--- a/tools/default_image.c
+++ b/tools/default_image.c
-@@ -98,7 +98,7 @@
+@@ -98,7 +98,7 @@ static void image_set_header(void *ptr,
sbuf->st_size - sizeof(image_header_t));
/* Build new header */
image_set_load(hdr, params->addr);
--- a/tools/imagetool.h
+++ b/tools/imagetool.h
-@@ -44,6 +44,7 @@
+@@ -44,6 +44,7 @@ struct image_tool_params {
int arch;
int type;
int comp;
--- /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
+@@ -4928,6 +4928,18 @@ within that device.
+ normal addressable memory via the LBC. CONFIG_SYS_LS_MC_FW_ADDR is the
+ virtual address in NOR flash.
+
++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
+@@ -89,6 +89,9 @@ static void image_set_header(void *ptr,
+ struct image_tool_params *params)
+ {
+ uint32_t checksum;
++ char *source_date_epoch;
++ struct tm *time_universal;
++ time_t time;
+
+ image_header_t * hdr = (image_header_t *)ptr;
+
+@@ -97,9 +100,25 @@ 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, params->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);