Make 'qemu-vexpress-a9' and 'imx6ul' use the same libcpu code.

components/lwp/SConscript

@@ -5,7 +5,7 @@ cwd     = GetCurrentDir()
 src     = []
 CPPPATH = [cwd]
 
-support_arch  = {"arm": ["cortex-m3", "cortex-m4", "cortex-m7", "arm926", "cortex-a9"]}
+support_arch  = {"arm": ["cortex-m3", "cortex-m4", "cortex-m7", "arm926", "cortex-a"]}
 platform_file = {'armcc': 'rvds.S', 'gcc': 'gcc.S', 'iar': 'iar.S'}
 
 if rtconfig.PLATFORM in platform_file.keys():	# support platforms

components/lwp/arch/arm/cortex-a/lwp_gcc.S

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2006-2018, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2018-12-10     Jesven       first version
+ */
+
+#define  Mode_USR       0x10
+#define  Mode_FIQ       0x11
+#define  Mode_IRQ       0x12
+#define  Mode_SVC       0x13
+#define  Mode_MON       0x16
+#define  Mode_ABT       0x17
+#define  Mode_UDF       0x1B
+#define  Mode_SYS       0x1F
+
+#define A_Bit        0x100 
+#define I_Bit        0x80 @; when I bit is set, IRQ is disabled
+#define F_Bit        0x40 @; when F bit is set, FIQ is disabled
+#define T_Bit        0x20
+
+.cpu cortex-a9
+.syntax unified
+.text
+
+/*
+ * void lwp_user_entry(args, text, data);
+ */
+.global lwp_user_entry
+.type lwp_user_entry, % function
+lwp_user_entry:
+    mrs     r9, cpsr
+    bic     r9, #0x1f
+    orr     r9, #Mode_USR
+    cpsid i
+    msr     spsr, r9
+
+    /* set data address. */
+    mov     r9, r2
+    movs    pc, r1
+
+/*
+ * void SVC_Handler(void);
+ */
+.global SVC_Handler
+.type SVC_Handler, % function
+SVC_Handler:
+    push {lr}
+    mrs lr, spsr
+    push {r4, r5, lr}
+    cpsie i
+
+    push {r0 - r3, r12}
+    and r0, r7, #0xff
+    bl lwp_get_sys_api
+    cmp r0, #0           /* r0 = api */
+    mov lr, r0
+    pop {r0 - r3, r12}
+    beq svc_exit
+    blx lr
+
+svc_exit:
+    cpsid i
+    pop {r4, r5, lr}
+    msr spsr_cxsf, lr
+    pop {lr}
+    movs pc, lr