src/shared/boot-timestamps.c

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