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Diffstat (limited to 'docs')
| -rw-r--r-- | docs/nvdimm.txt | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt index e903d8bb09..8b48fb4633 100644 --- a/docs/nvdimm.txt +++ b/docs/nvdimm.txt @@ -153,3 +153,30 @@ guest NVDIMM region mapping structure. This unarmed flag indicates 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 +--------------------- + +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: + + -machine pc,accel=kvm,nvdimm,nvdimm-cap=2 + +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. + +Here is a quick summary of the three bits that are defined as of that spec: + +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. |