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author | Ingo Molnar <mingo@elte.hu> | 2008-10-27 10:50:54 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-10-27 10:50:54 +0100 |
commit | 4944dd62de21230af039eda7cd218e9a09021d11 (patch) | |
tree | bac70f7bab8506c7e1b0408bacbdb0b1d77262e9 /arch/x86/include/asm/pvclock-abi.h | |
parent | ftrace: warning in kernel/trace/ftrace.c (diff) | |
parent | Linux 2.6.28-rc2 (diff) | |
download | linux-dev-4944dd62de21230af039eda7cd218e9a09021d11.tar.xz linux-dev-4944dd62de21230af039eda7cd218e9a09021d11.zip |
Merge commit 'v2.6.28-rc2' into tracing/urgent
Diffstat (limited to 'arch/x86/include/asm/pvclock-abi.h')
-rw-r--r-- | arch/x86/include/asm/pvclock-abi.h | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/arch/x86/include/asm/pvclock-abi.h b/arch/x86/include/asm/pvclock-abi.h new file mode 100644 index 000000000000..6d93508f2626 --- /dev/null +++ b/arch/x86/include/asm/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 */ |