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Diffstat (limited to 'docs/nvdimm.txt')
| -rw-r--r-- | docs/nvdimm.txt | 31 |
1 files changed, 12 insertions, 19 deletions
diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt index 8b48fb4633..24b443b655 100644 --- a/docs/nvdimm.txt +++ b/docs/nvdimm.txt @@ -154,29 +154,22 @@ guest software that this vNVDIMM device contains a region that cannot accept persistent writes. In result, for example, the guest Linux NVDIMM driver, marks such vNVDIMM device as read-only. -Platform Capabilities ---------------------- +NVDIMM Persistence +------------------ ACPI 6.2 Errata A added support for a new Platform Capabilities Structure which allows the platform to communicate what features it supports related to -NVDIMM data durability. Users can provide a capabilities value to a guest via -the optional "nvdimm-cap" machine command line option: +NVDIMM data persistence. Users can provide a persistence value to a guest via +the optional "nvdimm-persistence" machine command line option: - -machine pc,accel=kvm,nvdimm,nvdimm-cap=2 + -machine pc,accel=kvm,nvdimm,nvdimm-persistence=cpu -This "nvdimm-cap" field is an integer, and is the combined value of the -various capability bits defined in table 5-137 of the ACPI 6.2 Errata A spec. +There are currently two valid values for this option: -Here is a quick summary of the three bits that are defined as of that spec: +"mem-ctrl" - The platform supports flushing dirty data from the memory + controller to the NVDIMMs in the event of power loss. -Bit[0] - CPU Cache Flush to NVDIMM Durability on Power Loss Capable. -Bit[1] - Memory Controller Flush to NVDIMM Durability on Power Loss Capable. - Note: If bit 0 is set to 1 then this bit shall be set to 1 as well. -Bit[2] - Byte Addressable Persistent Memory Hardware Mirroring Capable. - -So, a "nvdimm-cap" value of 2 would mean that the platform supports Memory -Controller Flush on Power Loss, a value of 3 would mean that the platform -supports CPU Cache Flush and Memory Controller Flush on Power Loss, etc. - -For a complete list of the flags available and for more detailed descriptions, -please consult the ACPI spec. +"cpu" - The platform supports flushing dirty data from the CPU cache to + the NVDIMMs in the event of power loss. This implies that the + platform also supports flushing dirty data through the memory + controller on power loss. |