hw/acpi/aml-build: Make aml_buffer() definition consistent with the spec

According to ACPI spec, DefBuffer can take two parameters: BufferSize
and ByteList. Make it consistent with the spec. Uninitialized buffer
could be requested by passing ByteList as NULL to reserve space.

Signed-off-by: Shannon Zhao <zhaoshenglong@huawei.com>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 1432522520-8068-15-git-send-email-zhaoshenglong@huawei.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/acpi/aml-build.c

@@ -642,10 +642,22 @@ Aml *aml_resource_template(void)
     return var;
 }
 
-/* ACPI 1.0b: 16.2.5.4 Type 2 Opcodes Encoding: DefBuffer */
-Aml *aml_buffer(void)
+/* ACPI 1.0b: 16.2.5.4 Type 2 Opcodes Encoding: DefBuffer
+ * Pass byte_list as NULL to request uninitialized buffer to reserve space.
+ */
+Aml *aml_buffer(int buffer_size, uint8_t *byte_list)
 {
+    int i;
     Aml *var = aml_bundle(0x11 /* BufferOp */, AML_BUFFER);
+
+    for (i = 0; i < buffer_size; i++) {
+        if (byte_list == NULL) {
+            build_append_byte(var->buf, 0x0);
+        } else {
+            build_append_byte(var->buf, byte_list[i]);
+        }
+    }
+
     return var;
 }
 

include/hw/acpi/aml-build.h

@@ -253,7 +253,7 @@ Aml *aml_device(const char *name_format, ...) GCC_FMT_ATTR(1, 2);
 Aml *aml_method(const char *name, int arg_count);
 Aml *aml_if(Aml *predicate);
 Aml *aml_package(uint8_t num_elements);
-Aml *aml_buffer(void);
+Aml *aml_buffer(int buffer_size, uint8_t *byte_list);
 Aml *aml_resource_template(void);
 Aml *aml_field(const char *name, AmlAccessType type, AmlUpdateRule rule);
 Aml *aml_varpackage(uint32_t num_elements);