Merge tag 'hppa-btlb-pull-request' of https://github.com/hdeller/qemu-hppa into staging

[mirror_qemu.git] / docs / nvdimm.txt

diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt
index 362e99109e7b8458fcfee4d52194f1a26e1167aa..fd7773dc5abb5bc8abd261005af7e5b35502b022 100644 (file)
--- a/docs/nvdimm.txt
+++ b/docs/nvdimm.txt
@@ -15,10 +15,10 @@ backend (i.e. memory-backend-file and memory-backend-ram). A simple
 way to create a vNVDIMM device at startup time is done via the
 following command line options:
 
- -machine pc,nvdimm
+ -machine pc,nvdimm=on
  -m $RAM_SIZE,slots=$N,maxmem=$MAX_SIZE
- -object memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE
- -device nvdimm,id=nvdimm1,memdev=mem1
+ -object memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE,readonly=off
+ -device nvdimm,id=nvdimm1,memdev=mem1,unarmed=off
 
 Where,
 
@@ -31,9 +31,10 @@ Where,
    of normal RAM devices and vNVDIMM devices, e.g. $MAX_SIZE should be
    >= $RAM_SIZE + $NVDIMM_SIZE here.
 
- - "object memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE"
-   creates a backend storage of size $NVDIMM_SIZE on a file $PATH. All
-   accesses to the virtual NVDIMM device go to the file $PATH.
+ - "object memory-backend-file,id=mem1,share=on,mem-path=$PATH,
+   size=$NVDIMM_SIZE,readonly=off" creates a backend storage of size
+   $NVDIMM_SIZE on a file $PATH. All accesses to the virtual NVDIMM device go
+   to the file $PATH.
 
    "share=on/off" controls the visibility of guest writes. If
    "share=on", then guest writes will be applied to the backend
@@ -42,8 +43,17 @@ Where,
    "share=off", then guest writes won't be applied to the backend
    file and thus will be invisible to other guests.
 
- - "device nvdimm,id=nvdimm1,memdev=mem1" creates a virtual NVDIMM
-   device whose storage is provided by above memory backend device.
+   "readonly=on/off" controls whether the file $PATH is opened read-only or
+   read/write (default).
+
+ - "device nvdimm,id=nvdimm1,memdev=mem1,unarmed=off" creates a read/write
+   virtual NVDIMM device whose storage is provided by above memory backend
+   device.
+
+   "unarmed" controls the ACPI NFIT NVDIMM Region Mapping Structure "NVDIMM
+   State Flags" Bit 3 indicating that the device is "unarmed" and cannot accept
+   persistent writes. Linux guest drivers set the device to read-only when this
+   bit is present. Set unarmed to on when the memdev has readonly=on.
 
 Multiple vNVDIMM devices can be created if multiple pairs of "-object"
 and "-device" are provided.
@@ -132,6 +142,16 @@ address to the page size (getpagesize(2)) by default. However, some
 types of backends may require an alignment different than the page
 size. In that case, QEMU v2.12.0 and later provide 'align' option to
 memory-backend-file to allow users to specify the proper alignment.
+For device dax (e.g., /dev/dax0.0), this alignment needs to match the
+alignment requirement of the device dax. The NUM of 'align=NUM' option
+must be larger than or equal to the 'align' of device dax.
+We can use one of the following commands to show the 'align' of device dax.
+
+    ndctl list -X
+    daxctl list -R
+
+In order to get the proper 'align' of device dax, you need to install
+the library 'libdaxctl'.
 
 For example, device dax require the 2 MB alignment, so we can use
 following QEMU command line options to use it (/dev/dax0.0) as the