src/shared/boot-timestamps.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2012 Lennart Poettering
   5   Copyright 2013 Kay Sievers
   6
   7   systemd is free software; you can redistribute it and/or modify it
   8   under the terms of the GNU Lesser General Public License as published by
   9   the Free Software Foundation; either version 2.1 of the License, or
  10   (at your option) any later version.
  11
  12   systemd is distributed in the hope that it will be useful, but
  13   WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15   Lesser General Public License for more details.
  16
  17   You should have received a copy of the GNU Lesser General Public License
  18   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  19 ***/
  20
  21 #include "acpi-fpdt.h"
  22 #include "boot-timestamps.h"
  23 #include "efivars.h"
  24 #include "macro.h"
  25 #include "time-util.h"
  26
  27 int boot_timestamps(const dual_timestamp *n, dual_timestamp *firmware, dual_timestamp *loader) {
  28         usec_t x = 0, y = 0, a;
  29         int r;
  30         dual_timestamp _n;
  31
  32         assert(firmware);
  33         assert(loader);
  34
  35         if (!n) {
  36                 dual_timestamp_get(&_n);
  37                 n = &_n;
  38         }
  39
  40         r = acpi_get_boot_usec(&x, &y);
  41         if (r < 0) {
  42                 r = efi_loader_get_boot_usec(&x, &y);
  43                 if (r < 0)
  44                         return r;
  45         }
  46
  47         /* Let's convert this to timestamps where the firmware
  48          * began/loader began working. To make this more confusing:
  49          * since usec_t is unsigned and the kernel's monotonic clock
  50          * begins at kernel initialization we'll actually initialize
  51          * the monotonic timestamps here as negative of the actual
  52          * value. */
  53
  54         firmware->monotonic = y;
  55         loader->monotonic = y - x;
  56
  57         a = n->monotonic + firmware->monotonic;
  58         firmware->realtime = n->realtime > a ? n->realtime - a : 0;
  59
  60         a = n->monotonic + loader->monotonic;
  61         loader->realtime = n->realtime > a ? n->realtime - a : 0;
  62
  63         return 0;
  64 }