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authorIngo Molnar <mingo@kernel.org>2013-10-11 07:39:37 +0200
committerIngo Molnar <mingo@kernel.org>2013-10-11 07:39:37 +0200
commitec0ad3d01f99d5e5b56a99a58f7003b99250dc65 (patch)
tree85066cbea1cf8da6d099019adefaca90aae39234 /include/linux/timex.h
parent3354781a2184380046c8dd19144628d3c33991e6 (diff)
parent3f0116c3238a96bc18ad4b4acefe4e7be32fa861 (diff)
Merge branch 'core/urgent' into sched/core
Merge in asm goto fix, to be able to apply the asm/rmwcc.h fix. Signed-off-by: Ingo Molnar <mingo@kernel.org>
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 dd3edd7dfc9..9d3f1a5b617 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.