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-rw-r--r--Documentation/devicetree/bindings/chosen.txt48
1 files changed, 47 insertions, 1 deletions
diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
index 6ae9d82d4c37..dee3f5d9df26 100644
--- a/Documentation/devicetree/bindings/chosen.txt
+++ b/Documentation/devicetree/bindings/chosen.txt
@@ -10,7 +10,8 @@ stdout-path property
--------------------
Device trees may specify the device to be used for boot console output
-with a stdout-path property under /chosen, as described in ePAPR, e.g.
+with a stdout-path property under /chosen, as described in the Devicetree
+Specification, e.g.
/ {
chosen {
@@ -52,3 +53,48 @@ This property is set (currently only on PowerPC, and only needed on
book3e) by some versions of kexec-tools to tell the new kernel that it
is being booted by kexec, as the booting environment may differ (e.g.
a different secondary CPU release mechanism)
+
+linux,usable-memory-range
+-------------------------
+
+This property (arm64 only) holds a base address and size, describing a
+limited region in which memory may be considered available for use by
+the kernel. Memory outside of this range is not available for use.
+
+This property describes a limitation: memory within this range is only
+valid when also described through another mechanism that the kernel
+would otherwise use to determine available memory (e.g. memory nodes
+or the EFI memory map). Valid memory may be sparse within the range.
+e.g.
+
+/ {
+ chosen {
+ linux,usable-memory-range = <0x9 0xf0000000 0x0 0x10000000>;
+ };
+};
+
+The main usage is for crash dump kernel to identify its own usable
+memory and exclude, at its boot time, any other memory areas that are
+part of the panicked kernel's memory.
+
+While this property does not represent a real hardware, the address
+and the size are expressed in #address-cells and #size-cells,
+respectively, of the root node.
+
+linux,elfcorehdr
+----------------
+
+This property (currently used only on arm64) holds the memory range,
+the address and the size, of the elf core header which mainly describes
+the panicked kernel's memory layout as PT_LOAD segments of elf format.
+e.g.
+
+/ {
+ chosen {
+ linux,elfcorehdr = <0x9 0xfffff000 0x0 0x800>;
+ };
+};
+
+While this property does not represent a real hardware, the address
+and the size are expressed in #address-cells and #size-cells,
+respectively, of the root node.