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- 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);
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