support acpi firmware performance data (FPDT)

Prefer firmware-provided performance data over loader-exported ones; if
ACPI data is available, always use it, otherwise try to read the loader
data.

The firmware-provided variables start at the time the first EFI image
is executed and end when the operating system exits the boot services;
the (loader) time calculated in systemd-analyze increases.

1 files changed, 65 insertions, 0 deletions

diff --git a/src/shared/boot-timestamps.c b/src/shared/boot-timestamps.c
new file mode 100644
index 0000000000..944996582e
--- /dev/null
+++ b/src/shared/boot-timestamps.c
@@ -0,0 +1,65 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2012 Lennart Poettering
+  Copyright 2013 Kay Sievers
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+#include <unistd.h>
+
+#include "boot-timestamps.h"
+#include "acpi-fpdt.h"
+#include "efivars.h"
+
+int boot_timestamps(const dual_timestamp *n, dual_timestamp *firmware, dual_timestamp *loader) {
+        usec_t x, y, a;
+        int r;
+        dual_timestamp _n;
+
+        assert(firmware);
+        assert(loader);
+
+        if (!n) {
+                dual_timestamp_get(&_n);
+                n = &_n;
+        }
+
+        r = acpi_get_boot_usec(&x, &y);
+        if (r < 0) {
+                r = efi_loader_get_boot_usec(&x, &y);
+                if (r < 0)
+                        return r;
+        }
+
+        /* Let's convert this to timestamps where the firmware
+         * began/loader began working. To make this more confusing:
+         * since usec_t is unsigned and the kernel's monotonic clock
+         * begins at kernel initialization we'll actually initialize
+         * the monotonic timestamps here as negative of the actual
+         * value. */
+
+        firmware->monotonic = y;
+        loader->monotonic = y - x;
+
+        a = n->monotonic + firmware->monotonic;
+        firmware->realtime = n->realtime > a ? n->realtime - a : 0;
+
+        a = n->monotonic + loader->monotonic;
+        loader->realtime = n->realtime > a ? n->realtime - a : 0;
+
+        return 0;
+}