src/shared/boot-timestamps.c

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