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authorGleb Natapov <gleb@redhat.com>2013-10-17 17:04:47 +0300
committerGleb Natapov <gleb@redhat.com>2013-10-17 17:41:49 +0300
commit13acfd5715144518232d8e29acf7c76ef1b089d8 (patch)
tree093c4311a737210bbdd3d1919f8193cb5f017241 /include/linux/timex.h
parentd570142674890fe10b3d7d86aa105e3dfce1ddfa (diff)
parent34ec4de42be5006abdd8d0c08b306ffaa64d0d5d (diff)
Powerpc KVM work is based on a commit after rc4.
Merging master into next to satisfy the dependencies. Conflicts: arch/arm/kvm/reset.c
Diffstat (limited to 'include/linux/timex.h')
-rw-r--r--include/linux/timex.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/timex.h b/include/linux/timex.h
index dd3edd7dfc94..9d3f1a5b6178 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -64,6 +64,20 @@
#include <asm/timex.h>
+#ifndef random_get_entropy
+/*
+ * The random_get_entropy() function is used by the /dev/random driver
+ * in order to extract entropy via the relative unpredictability of
+ * when an interrupt takes places versus a high speed, fine-grained
+ * timing source or cycle counter. Since it will be occurred on every
+ * single interrupt, it must have a very low cost/overhead.
+ *
+ * By default we use get_cycles() for this purpose, but individual
+ * architectures may override this in their asm/timex.h header file.
+ */
+#define random_get_entropy() get_cycles()
+#endif
+
/*
* SHIFT_PLL is used as a dampening factor to define how much we
* adjust the frequency correction for a given offset in PLL mode.