src/shared/boot-timestamps.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2012 Lennart Poettering
   6   Copyright 2013 Kay Sievers
   7 ***/
   8
   9 #include "acpi-fpdt.h"
  10 #include "boot-timestamps.h"
  11 #include "efivars.h"
  12 #include "macro.h"
  13 #include "time-util.h"
  14
  15 int boot_timestamps(const dual_timestamp *n, dual_timestamp *firmware, dual_timestamp *loader) {
  16         usec_t x = 0, y = 0, a;
  17         int r;
  18         dual_timestamp _n;
  19
  20         assert(firmware);
  21         assert(loader);
  22
  23         if (!n) {
  24                 dual_timestamp_get(&_n);
  25                 n = &_n;
  26         }
  27
  28         r = acpi_get_boot_usec(&x, &y);
  29         if (r < 0) {
  30                 r = efi_loader_get_boot_usec(&x, &y);
  31                 if (r < 0)
  32                         return r;
  33         }
  34
  35         /* Let's convert this to timestamps where the firmware
  36          * began/loader began working. To make this more confusing:
  37          * since usec_t is unsigned and the kernel's monotonic clock
  38          * begins at kernel initialization we'll actually initialize
  39          * the monotonic timestamps here as negative of the actual
  40          * value. */
  41
  42         firmware->monotonic = y;
  43         loader->monotonic = y - x;
  44
  45         a = n->monotonic + firmware->monotonic;
  46         firmware->realtime = n->realtime > a ? n->realtime - a : 0;
  47
  48         a = n->monotonic + loader->monotonic;
  49         loader->realtime = n->realtime > a ? n->realtime - a : 0;
  50
  51         return 0;
  52 }