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authorJames Morse <james.morse@arm.com>2017-04-03 11:26:06 +0900
committerAKASHI Takahiro <takahiro.akashi@linaro.org>2017-06-08 19:19:37 +0900
commit844e91a54320a16bd8bdab543abc789ecea189c2 (patch)
treef5aed23275db9d1fbca4507c09aa3eb321a0f54b
parent9fd5d068c185f7bf5c945d1796321d3da862e92a (diff)
downloadlinux-aarch64-844e91a54320a16bd8bdab543abc789ecea189c2.tar.gz
Documentation: dt: chosen properties for arm64 kdump
Add documentation for DT properties: linux,usable-memory-range linux,elfcorehdr used by arm64 kdump. Those are, respectively, a usable memory range allocated to crash dump kernel and the elfcorehdr's location within it. Signed-off-by: James Morse <james.morse@arm.com> [takahiro.akashi@linaro.org: update the text due to recent changes ] Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Cc: devicetree@vger.kernel.org Cc: Rob Herring <robh+dt@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r--Documentation/devicetree/bindings/chosen.txt45
1 files changed, 45 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
index 6ae9d82d4c37..b5e39af4ddc0 100644
--- a/Documentation/devicetree/bindings/chosen.txt
+++ b/Documentation/devicetree/bindings/chosen.txt
@@ -52,3 +52,48 @@ 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.