@@ -79,9 +79,9 @@ 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 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
@@ -935,6 +935,29 @@ static void __init early_init_dt_check_for_elfcorehdr(unsigned long node)
elfcorehdr_addr, elfcorehdr_size);
}
+/**
+ * early_init_dt_check_for_usable_mem_range - Decode usable memory range
+ * location from flat tree
+ * @node: reference to node containing usable memory range location ('chosen')
+ */
+static void __init early_init_dt_check_for_usable_mem_range(unsigned long node)
+{
+ const __be32 *prop;
+ int len;
+
+ pr_debug("Looking for usable-memory-range property... ");
+
+ prop = of_get_flat_dt_prop(node, "linux,usable-memory-range", &len);
+ if (!prop || (len < (dt_root_addr_cells + dt_root_size_cells)))
+ return;
+
+ cap_mem_addr = dt_mem_next_cell(dt_root_addr_cells, &prop);
+ cap_mem_size = dt_mem_next_cell(dt_root_size_cells, &prop);
+
+ pr_debug("cap_mem_start=%pa cap_mem_size=%pa\n", &cap_mem_addr,
+ &cap_mem_size);
+}
+
#ifdef CONFIG_SERIAL_EARLYCON
int __init early_init_dt_scan_chosen_stdout(void)
@@ -1083,6 +1106,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
early_init_dt_check_for_initrd(node);
early_init_dt_check_for_elfcorehdr(node);
+ early_init_dt_check_for_usable_mem_range(node);
/* Retrieve command line */
p = of_get_flat_dt_prop(node, "bootargs", &l);
Add support for parsing the "linux,usable-memory-range" property in the "/chosen" node to the FDT core code. This can co-exist safely with the architecture-specific parsing, until the latter has been removed. Architecture-specific code still has to make sure the resulting memory range limitation is applied, if present. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- About the change to chosen.txt: I have a similar change for schemas/chosen.yaml in dt-schema. v4: - New. --- Documentation/devicetree/bindings/chosen.txt | 6 ++--- drivers/of/fdt.c | 24 ++++++++++++++++++++ 2 files changed, 27 insertions(+), 3 deletions(-)