Enable ALSA debug in kernel

Now gets "virtio_snd: probe of virtio2 failed with error -2" in
dmesg.

Makefile

@@ -2,7 +2,7 @@ include mk/common.mk
 
 CC ?= gcc
 CFLAGS := -O2 -g -Wall -Wextra
-CFLAGS += -include common.h
+CFLAGS += -include common.h -I./cnfa
 
 # clock frequency
 CLOCK_FREQ ?= 65000000
@@ -13,6 +13,8 @@ OBJS_EXTRA :=
 # command line option
 OPTS :=
 
+LDFLAGS :=
+
 # virtio-blk
 ENABLE_VIRTIOBLK ?= 1
 $(call set-feature, VIRTIOBLK)
@@ -41,8 +43,20 @@ ifeq ($(call has, VIRTIONET), 1)
     OBJS_EXTRA += virtio-net.o
 endif
 
+# virtio-snd
+ENABLE_VIRTIOSND ?= 1
+ifneq ($(UNAME_S),Linux)
+    ENABLE_VIRTIOSND := 0
+endif
+$(call set-feature, VIRTIOSND)
+ifeq ($(call has, VIRTIOSND), 1)
+    OBJS_EXTRA += virtio-snd.o
+    LDFLAGS += -lasound
+    CFLAGS += -I/usr/local/include
+endif
+
 BIN = semu
-all: $(BIN) minimal.dtb
+all: cnfa_dep $(BIN) minimal.dtb
 
 OBJS := \
 	riscv.o \
@@ -56,6 +70,11 @@ OBJS := \
 
 deps := $(OBJS:%.o=.%.o.d)
 
+cnfa_dep:
+	rm cnfa/CNFA_sf.h
+	make -C cnfa os_generic.h
+	make -C cnfa CNFA_sf.h
+
 $(BIN): $(OBJS)
 	$(VECHO) "  LD\t$@\n"
 	$(Q)$(CC) -o $@ $^ $(LDFLAGS)

configs/buildroot.config

@@ -36,6 +36,9 @@ BR2_RELRO_NONE=y
 # BR2_RELRO_PARTIAL is not set
 # BR2_RELRO_FULL is not set
 BR2_FORTIFY_SOURCE_1=y
+BR2_PACKAGE_ALSA_UTILS=y
+BR2_PACKAGE_ALSA_UTILS_APLAY=y
+BR2_PACKAGE_ALSA_UTILS_SPEAKER_TEST=y
 # BR2_PACKAGE_URANDOM_SCRIPTS is not set
 BR2_TARGET_ROOTFS_CPIO=y
 BR2_TARGET_ROOTFS_CPIO_FULL=y