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authorIngo Molnar <mingo@elte.hu>2008-07-06 14:23:39 +0200
committerIngo Molnar <mingo@elte.hu>2008-07-06 14:23:39 +0200
commit68083e05d72d94f347293d8cc0067050ba904bfa (patch)
tree842e71365bd90866be7add181661a4039d891564 /include/asm-x86/pvclock-abi.h
parent7baac8b91f9871ba8cb09af84de4ae1d86d07812 (diff)
parentb7279469d66b55119784b8b9529c99c1955fe747 (diff)
Merge commit 'v2.6.26-rc9' into cpus4096
Diffstat (limited to 'include/asm-x86/pvclock-abi.h')
-rw-r--r--include/asm-x86/pvclock-abi.h42
1 files changed, 42 insertions, 0 deletions
diff --git a/include/asm-x86/pvclock-abi.h b/include/asm-x86/pvclock-abi.h
new file mode 100644
index 000000000000..6857f840b243
--- /dev/null
+++ b/include/asm-x86/pvclock-abi.h
@@ -0,0 +1,42 @@
+#ifndef _ASM_X86_PVCLOCK_ABI_H_
+#define _ASM_X86_PVCLOCK_ABI_H_
+#ifndef __ASSEMBLY__
+
+/*
+ * These structs MUST NOT be changed.
+ * They are the ABI between hypervisor and guest OS.
+ * Both Xen and KVM are using this.
+ *
+ * pvclock_vcpu_time_info holds the system time and the tsc timestamp
+ * of the last update. So the guest can use the tsc delta to get a
+ * more precise system time. There is one per virtual cpu.
+ *
+ * pvclock_wall_clock references the point in time when the system
+ * time was zero (usually boot time), thus the guest calculates the
+ * current wall clock by adding the system time.
+ *
+ * Protocol for the "version" fields is: hypervisor raises it (making
+ * it uneven) before it starts updating the fields and raises it again
+ * (making it even) when it is done. Thus the guest can make sure the
+ * time values it got are consistent by checking the version before
+ * and after reading them.
+ */
+
+struct pvclock_vcpu_time_info {
+ u32 version;
+ u32 pad0;
+ u64 tsc_timestamp;
+ u64 system_time;
+ u32 tsc_to_system_mul;
+ s8 tsc_shift;
+ u8 pad[3];
+} __attribute__((__packed__)); /* 32 bytes */
+
+struct pvclock_wall_clock {
+ u32 version;
+ u32 sec;
+ u32 nsec;
+} __attribute__((__packed__));
+
+#endif /* __ASSEMBLY__ */
+#endif /* _ASM_X86_PVCLOCK_ABI_H_ */