mirror of https://gitee.com/openkylin/linux.git
66 lines
2.1 KiB
Plaintext
66 lines
2.1 KiB
Plaintext
Device-tree bindings for persistent memory regions
|
|
-----------------------------------------------------
|
|
|
|
Persistent memory refers to a class of memory devices that are:
|
|
|
|
a) Usable as main system memory (i.e. cacheable), and
|
|
b) Retain their contents across power failure.
|
|
|
|
Given b) it is best to think of persistent memory as a kind of memory mapped
|
|
storage device. To ensure data integrity the operating system needs to manage
|
|
persistent regions separately to the normal memory pool. To aid with that this
|
|
binding provides a standardised interface for discovering where persistent
|
|
memory regions exist inside the physical address space.
|
|
|
|
Bindings for the region nodes:
|
|
-----------------------------
|
|
|
|
Required properties:
|
|
- compatible = "pmem-region"
|
|
|
|
- reg = <base, size>;
|
|
The reg property should specificy an address range that is
|
|
translatable to a system physical address range. This address
|
|
range should be mappable as normal system memory would be
|
|
(i.e cacheable).
|
|
|
|
If the reg property contains multiple address ranges
|
|
each address range will be treated as though it was specified
|
|
in a separate device node. Having multiple address ranges in a
|
|
node implies no special relationship between the two ranges.
|
|
|
|
Optional properties:
|
|
- Any relevant NUMA assocativity properties for the target platform.
|
|
|
|
- volatile; This property indicates that this region is actually
|
|
backed by non-persistent memory. This lets the OS know that it
|
|
may skip the cache flushes required to ensure data is made
|
|
persistent after a write.
|
|
|
|
If this property is absent then the OS must assume that the region
|
|
is backed by non-volatile memory.
|
|
|
|
Examples:
|
|
--------------------
|
|
|
|
/*
|
|
* This node specifies one 4KB region spanning from
|
|
* 0x5000 to 0x5fff that is backed by non-volatile memory.
|
|
*/
|
|
pmem@5000 {
|
|
compatible = "pmem-region";
|
|
reg = <0x00005000 0x00001000>;
|
|
};
|
|
|
|
/*
|
|
* This node specifies two 4KB regions that are backed by
|
|
* volatile (normal) memory.
|
|
*/
|
|
pmem@6000 {
|
|
compatible = "pmem-region";
|
|
reg = < 0x00006000 0x00001000
|
|
0x00008000 0x00001000 >;
|
|
volatile;
|
|
};
|
|
|