diff options
| author | Junyan He <junyan.he@intel.com> | 2018-07-18 15:48:00 +0800 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2018-08-10 13:29:39 +0300 |
| commit | a4de8552b2580adf6fa4874439217b65d3bdd88b (patch) | |
| tree | 0cfd280873e9c1a616d17d88a06bc9f32863e2d4 /docs | |
| parent | 17824406fa55b303379f2e4af715c1e876c3535f (diff) | |
hostmem-file: add the 'pmem' option
When QEMU emulates vNVDIMM labels and migrates vNVDIMM devices, it
needs to know whether the backend storage is a real persistent memory,
in order to decide whether special operations should be performed to
ensure the data persistence.
This boolean option 'pmem' allows users to specify whether the backend
storage of memory-backend-file is a real persistent memory. If
'pmem=on', QEMU will set the flag RAM_PMEM in the RAM block of the
corresponding memory region. If 'pmem' is set while lack of libpmem
support, a error is generated.
Signed-off-by: Junyan He <junyan.he@intel.com>
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/nvdimm.txt | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt index 24b443b655..5f158a6170 100644 --- a/docs/nvdimm.txt +++ b/docs/nvdimm.txt @@ -173,3 +173,25 @@ There are currently two valid values for this option: 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. + +If the vNVDIMM backend is in host persistent memory that can be accessed in +SNIA NVM Programming Model [1] (e.g., Intel NVDIMM), it's suggested to set +the 'pmem' option of memory-backend-file to 'on'. When 'pmem' is 'on' and QEMU +is built with libpmem [2] support (configured with --enable-libpmem), QEMU +will take necessary operations to guarantee the persistence of its own writes +to the vNVDIMM backend(e.g., in vNVDIMM label emulation and live migration). +If 'pmem' is 'on' while there is no libpmem support, qemu will exit and report +a "lack of libpmem support" message to ensure the persistence is available. +For example, if we want to ensure the persistence for some backend file, +use the QEMU command line: + + -object memory-backend-file,id=nv_mem,mem-path=/XXX/yyy,size=4G,pmem=on + +References +---------- + +[1] NVM Programming Model (NPM) + Version 1.2 + https://www.snia.org/sites/default/files/technical_work/final/NVMProgrammingModel_v1.2.pdf +[2] Persistent Memory Development Kit (PMDK), formerly known as NVML project, home page: + http://pmem.io/pmdk/ |