ARC: mm: document system mem map clearly
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h
index 649e439..ee682d8 100644
--- a/arch/arc/include/asm/processor.h
+++ b/arch/arc/include/asm/processor.h
@@ -100,29 +100,26 @@
#endif /* !__ASSEMBLY__ */
-/* Kernels Virtual memory area.
- * Unlike other architectures(MIPS, sh, cris ) ARC 700 does not have a
- * "kernel translated" region (like KSEG2 in MIPS). So we use a upper part
- * of the translated bottom 2GB for kernel virtual memory and protect
- * these pages from user accesses by disabling Ru, Eu and Wu.
+/*
+ * System Memory Map on ARC
+ *
+ * ---------------------------- (lower 2G, Translated) -------------------------
+ * 0x0000_0000 0x5FFF_FFFF (user vaddr: TASK_SIZE)
+ * 0x6000_0000 0x6FFF_FFFF (reserved gutter between U/K)
+ * 0x7000_0000 0x7FFF_FFFF (kvaddr: vmalloc/modules/pkmap..)
+ *
+ * PAGE_OFFSET ---------------- (Upper 2G, Untranslated) -----------------------
+ * 0x8000_0000 0xBFFF_FFFF (kernel direct mapped)
+ * 0xC000_0000 0xFFFF_FFFF (peripheral uncached space)
+ * -----------------------------------------------------------------------------
*/
-#define VMALLOC_SIZE (0x10000000) /* 256M */
-#define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE)
-#define VMALLOC_END (PAGE_OFFSET)
+#define VMALLOC_START 0x70000000
+#define VMALLOC_SIZE (PAGE_OFFSET - VMALLOC_START)
+#define VMALLOC_END (VMALLOC_START + VMALLOC_SIZE)
-/* Most of the architectures seem to be keeping some kind of padding between
- * userspace TASK_SIZE and PAGE_OFFSET. i.e TASK_SIZE != PAGE_OFFSET.
- */
#define USER_KERNEL_GUTTER 0x10000000
-/* User address space:
- * On ARC700, CPU allows the entire lower half of 32 bit address space to be
- * translated. Thus potentially 2G (0:0x7FFF_FFFF) could be User vaddr space.
- * However we steal 256M for kernel addr (0x7000_0000:0x7FFF_FFFF) and another
- * 256M (0x6000_0000:0x6FFF_FFFF) is gutter between user/kernel spaces
- * Thus total User vaddr space is (0:0x5FFF_FFFF)
- */
-#define TASK_SIZE (PAGE_OFFSET - VMALLOC_SIZE - USER_KERNEL_GUTTER)
+#define TASK_SIZE (VMALLOC_START - USER_KERNEL_GUTTER)
#define STACK_TOP TASK_SIZE
#define STACK_TOP_MAX STACK_TOP