[PATCH] avr: Fix wrong initial value of stack pointer

[Gihun Nam]

The current implementation initializes the stack pointer of AVR devices
to 0, but it should be set to RAMEND according to the specs.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1525
Signed-off-by: Gihun Nam <gihun.nam@outlook.com>
---
 hw/avr/atmega.c  | 3 +++
 target/avr/cpu.c | 2 +-
 target/avr/cpu.h | 3 +++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/hw/avr/atmega.c b/hw/avr/atmega.c
index a34803e642..3a8caccf99 100644
--- a/hw/avr/atmega.c
+++ b/hw/avr/atmega.c
@@ -233,6 +233,9 @@ static void atmega_realize(DeviceState *dev, Error **errp)
 
     /* CPU */
     object_initialize_child(OBJECT(dev), "cpu", &s->cpu, mc->cpu_type);
+
+    s->cpu.init_sp = mc->io_size + mc->sram_size - 1;
+
     qdev_realize(DEVICE(&s->cpu), NULL, &error_abort);
     cpudev = DEVICE(&s->cpu);
 
diff --git a/target/avr/cpu.c b/target/avr/cpu.c
index 44de1e18d1..1da7d7dbf3 100644
--- a/target/avr/cpu.c
+++ b/target/avr/cpu.c
@@ -95,7 +95,7 @@ static void avr_cpu_reset_hold(Object *obj)
     env->rampY = 0;
     env->rampZ = 0;
     env->eind = 0;
-    env->sp = 0;
+    env->sp = cpu->init_sp;
 
     env->skip = 0;
 
diff --git a/target/avr/cpu.h b/target/avr/cpu.h
index 8a17862737..7960c5c57a 100644
--- a/target/avr/cpu.h
+++ b/target/avr/cpu.h
@@ -145,6 +145,9 @@ struct ArchCPU {
     CPUState parent_obj;
 
     CPUAVRState env;
+
+    /* Initial value of stack pointer */
+    uint32_t init_sp;
 };
 
 /**
-- 
2.39.2