diff options
| author | David Woodhouse <David.Woodhouse@intel.com> | 2012-10-09 15:03:21 +0100 |
|---|---|---|
| committer | David Woodhouse <David.Woodhouse@intel.com> | 2012-10-09 15:04:25 +0100 |
| commit | ffe315012510165ce82e4dd4767f0a5dba9edbf7 (patch) | |
| tree | f601cd980af9d0ced5ca9aedecef4fa0d2ca0e15 /Documentation/virtual/kvm/msr.txt | |
| parent | e2d3a35ee427aaba99b6c68a56609ce276c51270 (diff) | |
| parent | 4a8e43feeac7996b8de2d5b2823e316917493df4 (diff) | |
Merge tag 'disintegrate-mtd-20121009' of git://git.infradead.org/users/dhowells/linux-headers
UAPI Disintegration 2012-10-09
Conflicts:
MAINTAINERS
arch/arm/configs/bcmring_defconfig
arch/arm/mach-imx/clk-imx51-imx53.c
drivers/mtd/nand/Kconfig
drivers/mtd/nand/bcm_umi_nand.c
drivers/mtd/nand/nand_bcm_umi.h
drivers/mtd/nand/orion_nand.c
Diffstat (limited to 'Documentation/virtual/kvm/msr.txt')
| -rw-r--r-- | Documentation/virtual/kvm/msr.txt | 32 |
1 files changed, 20 insertions, 12 deletions
diff --git a/Documentation/virtual/kvm/msr.txt b/Documentation/virtual/kvm/msr.txt index 73047104858..6d470ae7b07 100644 --- a/Documentation/virtual/kvm/msr.txt +++ b/Documentation/virtual/kvm/msr.txt @@ -34,9 +34,12 @@ MSR_KVM_WALL_CLOCK_NEW: 0x4b564d00 time information and check that they are both equal and even. An odd version indicates an in-progress update. - sec: number of seconds for wallclock. + sec: number of seconds for wallclock at time of boot. - nsec: number of nanoseconds for wallclock. + nsec: number of nanoseconds for wallclock at time of boot. + + In order to get the current wallclock time, the system_time from + MSR_KVM_SYSTEM_TIME_NEW needs to be added. Note that although MSRs are per-CPU entities, the effect of this particular MSR is global. @@ -82,20 +85,25 @@ MSR_KVM_SYSTEM_TIME_NEW: 0x4b564d01 time at the time this structure was last updated. Unit is nanoseconds. - tsc_to_system_mul: a function of the tsc frequency. One has - to multiply any tsc-related quantity by this value to get - a value in nanoseconds, besides dividing by 2^tsc_shift + tsc_to_system_mul: multiplier to be used when converting + tsc-related quantity to nanoseconds - tsc_shift: cycle to nanosecond divider, as a power of two, to - allow for shift rights. One has to shift right any tsc-related - quantity by this value to get a value in nanoseconds, besides - multiplying by tsc_to_system_mul. + tsc_shift: shift to be used when converting tsc-related + quantity to nanoseconds. This shift will ensure that + multiplication with tsc_to_system_mul does not overflow. + A positive value denotes a left shift, a negative value + a right shift. - With this information, guests can derive per-CPU time by - doing: + The conversion from tsc to nanoseconds involves an additional + right shift by 32 bits. With this information, guests can + derive per-CPU time by doing: time = (current_tsc - tsc_timestamp) - time = (time * tsc_to_system_mul) >> tsc_shift + if (tsc_shift >= 0) + time <<= tsc_shift; + else + time >>= -tsc_shift; + time = (time * tsc_to_system_mul) >> 32 time = time + system_time flags: bits in this field indicate extended capabilities |