!526 aarch64 启动文件增加 RT_NEED_FLUSH_DCACHE_ALL 选项

Merge pull request !526 from WillianChan/WillianChan

libcpu/Kconfig

@@ -9,6 +9,10 @@ config RT_USING_CPU_FFS
     bool
     default n
 
+config ARCH_ARM_BOOTWITH_FLUSH_CACHE
+    bool
+    default n
+
 config ARCH_CPU_STACK_GROWS_UPWARD
     bool
     default n

libcpu/aarch64/cortex-a/entry_point.S

@@ -13,6 +13,9 @@
 .global __start
 
 __start:
+#ifdef ARCH_ARM_BOOTWITH_FLUSH_CACHE
+    bl      __asm_flush_dcache_all
+#endif
     bl      rt_hw_cpu_id_set
     /* read cpu id, stop slave cores */
     mrs     x0, tpidr_el1