Patchwork [v31,12/12] Documentation: dt: chosen properties for arm64 kdump

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Submitter AKASHI Takahiro
Date Feb. 1, 2017, 12:48 p.m.
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Permalink /patch/164763/
State New
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AKASHI Takahiro - Feb. 1, 2017, 12:48 p.m.
From: James Morse <>

Add documentation for DT properties:
used by arm64 kdump. Those decribe the usable memory range for crash dump
kernel and the elfcorehdr's location within it, respectively.

Signed-off-by: James Morse <>
[ added "linux,crashkernel-base" and "-size" ]
Signed-off-by: AKASHI Takahiro <>
Acked-by: Mark Rutland <>
Cc: Rob Herring <>
 Documentation/devicetree/bindings/chosen.txt | 37 ++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)


diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
index 6ae9d82d4c37..8dc82431acc1 100644
--- a/Documentation/devicetree/bindings/chosen.txt
+++ b/Documentation/devicetree/bindings/chosen.txt
@@ -52,3 +52,40 @@  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)
+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.
+/ {
+	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.
+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.
+/ {
+	chosen {
+		linux,elfcorehdr = <0x9 0xfffff000 0x0 0x800>;
+	};