83 lines
2.6 KiB
Diff
83 lines
2.6 KiB
Diff
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From f3f431a712729a1af94d01bd1bfde17a252ff02c Mon Sep 17 00:00:00 2001
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From: Paul Kocialkowski <contact@paulk.fr>
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Date: Sun, 26 Jul 2015 18:48:15 +0200
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Subject: [PATCH] Reproducible U-Boot build support, using SOURCE_DATE_EPOCH
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In order to achieve reproducible builds in U-Boot, timestamps that are defined
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at build-time have to be somewhat eliminated. The SOURCE_DATE_EPOCH environment
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variable allows setting a fixed value for those timestamps.
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Simply by setting SOURCE_DATE_EPOCH to a fixed value, a number of targets can be
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built reproducibly. This is the case for e.g. sunxi devices.
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However, some other devices might need some more tweaks, especially regarding
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the image generation tools.
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Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
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---
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Makefile | 7 ++++---
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README | 12 ++++++++++++
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tools/default_image.c | 21 ++++++++++++++++++++-
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3 files changed, 36 insertions(+), 4 deletions(-)
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--- a/README
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+++ b/README
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@@ -4928,6 +4928,18 @@ within that device.
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normal addressable memory via the LBC. CONFIG_SYS_LS_MC_FW_ADDR is the
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virtual address in NOR flash.
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+Reproducible builds
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+-------------------
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+
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+In order to achieve reproducible builds, timestamps used in the U-Boot build
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+process have to be set to a fixed value.
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+
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+This is done using the SOURCE_DATE_EPOCH environment variable.
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+SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
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+option for U-Boot or an environment variable in U-Boot.
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+
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+SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
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+
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Building the Software:
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======================
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--- a/tools/default_image.c
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+++ b/tools/default_image.c
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@@ -89,6 +89,9 @@ static void image_set_header(void *ptr,
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struct image_tool_params *params)
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{
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uint32_t checksum;
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+ char *source_date_epoch;
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+ struct tm *time_universal;
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+ time_t time;
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image_header_t * hdr = (image_header_t *)ptr;
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@@ -97,9 +100,25 @@ static void image_set_header(void *ptr,
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sizeof(image_header_t)),
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sbuf->st_size - sizeof(image_header_t));
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+ source_date_epoch = getenv("SOURCE_DATE_EPOCH");
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+ if (source_date_epoch != NULL) {
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+ time = (time_t) strtol(source_date_epoch, NULL, 10);
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+
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+ time_universal = gmtime(&time);
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+ if (time_universal == NULL) {
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+ fprintf(stderr, "%s: SOURCE_DATE_EPOCH is not valid\n",
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+ __func__);
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+ time = 0;
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+ } else {
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+ time = mktime(time_universal);
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+ }
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+ } else {
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+ time = sbuf->st_mtime;
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+ }
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+
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/* Build new header */
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image_set_magic(hdr, params->magic);
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- image_set_time(hdr, sbuf->st_mtime);
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+ image_set_time(hdr, time);
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image_set_size(hdr, sbuf->st_size - sizeof(image_header_t));
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image_set_load(hdr, params->addr);
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image_set_ep(hdr, params->ep);
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