From ea659643ee1b0c46e473619034cd130440405ac4 Mon Sep 17 00:00:00 2001
From: Narayan Kamath <narayan@google.com>
Date: Thu, 10 Apr 2014 18:40:55 +0100
Subject: [PATCH] HAVE_POSIX_CLOCKS doesn't imply CLOCK_BOOTTIME.

HAVE_POSIX_CLOCKS imples clock_gettime,settime and
CLOCK_REALTIME / CLOCK_MONOTONIC.

CLOCK_BOOTTIME appears only on newer versions of glibc
and might only be supported on newer kernels.

Change-Id: I66e724a3593538c3b80de2c5f81a964d3fa96eaf
---
 libutils/Timers.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libutils/Timers.cpp b/libutils/Timers.cpp
index 5293cd2a8..a431e9232 100644
--- a/libutils/Timers.cpp
+++ b/libutils/Timers.cpp
@@ -34,7 +34,7 @@
 
 nsecs_t systemTime(int clock)
 {
-#if defined(HAVE_POSIX_CLOCKS)
+#if defined(HAVE_ANDROID_OS)
     static const clockid_t clocks[] = {
             CLOCK_REALTIME,
             CLOCK_MONOTONIC,
@@ -47,7 +47,9 @@ nsecs_t systemTime(int clock)
     clock_gettime(clocks[clock], &t);
     return nsecs_t(t.tv_sec)*1000000000LL + t.tv_nsec;
 #else
-    // we don't support the clocks here.
+    // Clock support varies widely across hosts. Mac OS doesn't support
+    // posix clocks, older glibcs don't support CLOCK_BOOTTIME and Windows
+    // is windows.
     struct timeval t;
     t.tv_sec = t.tv_usec = 0;
     gettimeofday(&t, NULL);