initial work for aarch64 support

kernel/make.aarch64.config

@@ -1 +0,0 @@
-LD=arm-none-eabi-ld

kernel/make/aarch64/linker.ld

@@ -0,0 +1,43 @@
+ENTRY(_start)
+ 
+SECTIONS
+{
+    /* Starts at LOADER_ADDR. */
+    . = 0x80000;
+    __start = .;
+    __text_start = .;
+    .text :
+    {
+        KEEP(*(.text.boot))
+        *(.text)
+    }
+    . = ALIGN(4096); /* align to page size */
+    __text_end = .;
+ 
+    __rodata_start = .;
+    .rodata :
+    {
+        *(.rodata)
+    }
+    . = ALIGN(4096); /* align to page size */
+    __rodata_end = .;
+ 
+    __data_start = .;
+    .data :
+    {
+        *(.data)
+    }
+    . = ALIGN(4096); /* align to page size */
+    __data_end = .;
+ 
+    __bss_start = .;
+    .bss :
+    {
+        bss = .;
+        *(.bss)
+    }
+    . = ALIGN(4096); /* align to page size */
+    __bss_end = .;
+    __bss_size = __bss_end - __bss_start;
+    __end = .;
+}

kernel/make/aarch64/make.config

@@ -0,0 +1 @@
+LD=aarch64-linux-gnu-ld