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Subject[PATCH v7 15/16] ARM: LPAE: add support for ATAG_MEM64
Date
From: Will Deacon <will.deacon@arm.com>

LPAE provides support for memory banks with physical addresses of up
to 40 bits.

This patch adds a new atag, ATAG_MEM64, so that the Kernel can be
informed about memory that exists above the 4GB boundary.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm/include/asm/setup.h | 8 ++++++++
arch/arm/kernel/setup.c | 10 ++++++++++
2 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/arch/arm/include/asm/setup.h b/arch/arm/include/asm/setup.h
index 915696d..a3ca303 100644
--- a/arch/arm/include/asm/setup.h
+++ b/arch/arm/include/asm/setup.h
@@ -43,6 +43,13 @@ struct tag_mem32 {
__u32 start; /* physical start address */
};

+#define ATAG_MEM64 0x54420002
+
+struct tag_mem64 {
+ __u64 size;
+ __u64 start; /* physical start address */
+};
+
/* VGA text type displays */
#define ATAG_VIDEOTEXT 0x54410003

@@ -148,6 +155,7 @@ struct tag {
union {
struct tag_core core;
struct tag_mem32 mem;
+ struct tag_mem64 mem64;
struct tag_videotext videotext;
struct tag_ramdisk ramdisk;
struct tag_initrd initrd;
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 70bca64..a126558 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -608,6 +608,16 @@ static int __init parse_tag_mem32(const struct tag *tag)

__tagtable(ATAG_MEM, parse_tag_mem32);

+#ifdef CONFIG_PHYS_ADDR_T_64BIT
+static int __init parse_tag_mem64(const struct tag *tag)
+{
+ /* We only use 32-bits for the size. */
+ return arm_add_memory(tag->u.mem64.start, (unsigned long)tag->u.mem64.size);
+}
+
+__tagtable(ATAG_MEM64, parse_tag_mem64);
+#endif /* CONFIG_PHYS_ADDR_T_64BIT */
+
#if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE)
struct screen_info screen_info = {
.orig_video_lines = 30,


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