[Qemu-devel] [patch] Arm CPU halt support

[Qemu-devel] [patch] Arm CPU halt support

[Paul Brook]

[-- Attachment #1: Type: text/plain, Size: 58 bytes --]

The attached patch implements Arm CPU suspend/halt.

Paul

[-- Attachment #2: patch.qemu_arm_halt --]
[-- Type: text/x-diff, Size: 2032 bytes --]

=== cpu-exec.c
==================================================================
--- cpu-exec.c	(revision 1861)
+++ cpu-exec.c	(local)
@@ -274,6 +274,17 @@
             return EXCP_HALTED;
         }
     }
+#elif defined(TARGET_ARM)
+    if (env1->halted) {
+        /* An interrupt wakes the CPU even if the I and F CPSR bits are
+           set.  */
+        if (env1->interrupt_request
+            & (CPU_INTERRUPT_FIQ | CPU_INTERRUPT_HARD)) {
+            env1->halted = 0;
+        } else {
+            return EXCP_HALTED;
+        }
+    }
 #endif
 
     cpu_single_env = env1; 
=== target-arm/cpu.h
==================================================================
--- target-arm/cpu.h	(revision 1861)
+++ target-arm/cpu.h	(local)
@@ -90,7 +90,7 @@
     int exception_index;
     int interrupt_request;
     int user_mode_only;
-    uint32_t address;
+    int halted;
 
     /* VFP coprocessor state.  */
     struct {
=== target-arm/op.c
==================================================================
--- target-arm/op.c	(revision 1861)
+++ target-arm/op.c	(local)
@@ -878,6 +878,13 @@
     cpu_loop_exit();
 }
 
+void OPPROTO op_wfi(void)
+{
+    env->exception_index = EXCP_HLT;
+    env->halted = 1;
+    cpu_loop_exit();
+}
+
 /* VFP support.  We follow the convention used for VFP instrunctions:
    Single precition routines have a "s" suffix, double precision a
    "d" suffix.  */
=== target-arm/translate.c
==================================================================
--- target-arm/translate.c	(revision 1861)
+++ target-arm/translate.c	(local)
@@ -496,6 +496,15 @@
     if (IS_USER(s)) {
         return 1;
     }
+    if ((insn & 0x0fff0fff) == 0x0e070f90
+        || (insn & 0x0fff0fff) == 0x0e070f58) {
+        /* Wait for interrupt.  */
+        gen_op_movl_T0_im((long)s->pc);
+        gen_op_movl_reg_TN[0][15]();
+        gen_op_wfi();
+        s->is_jmp = DISAS_JUMP;
+        return 0;
+    }
     rd = (insn >> 12) & 0xf;
     if (insn & (1 << 20)) {
         gen_op_movl_T0_cp15(insn);

[Qemu-devel] Re: [patch] Arm CPU halt support

[Antti P Miettinen]

Paul Brook <paul@codesourcery.com> writes:
> The attached patch implements Arm CPU suspend/halt.

Just to confirm: the busy looping is gone with the patch applied.