Migrate virtio-snd from semu

.ci/boot-linux.sh

@@ -50,4 +50,10 @@ if grep -q '^CONFIG_VIRTIO_NET_VMNET=y$' .config; then
     RET=$((${RET} + $?))
 fi
 
+# Virtio-snd tests
+if grep -q '^CONFIG_VIRTIO_SND=y$' .config; then
+    (. "${SCRIPT_DIR}/sound.sh")
+    RET=$((${RET} + $?))
+fi
+
 exit ${RET}

.ci/brew-install.sh

@@ -14,7 +14,7 @@ set -e -u -o pipefail
 
 LLVM_VERSION=$(cat "${SCRIPT_DIR}/llvm-version")
 
-brew install make dtc expect sdl2 bc e2fsprogs p7zip "llvm@${LLVM_VERSION}" dcfldd
+brew install make dtc expect sdl2 bc e2fsprogs p7zip "llvm@${LLVM_VERSION}" dcfldd pkgconf portaudio
 
 # SDL_mixer only gates the audio tests, so a bottle outage should not take the
 # whole job down with it.
@@ -24,12 +24,12 @@ brew install sdl2_mixer \
 # Relink every formula the later build steps invoke by name. Failures are
 # tolerated (a keg-only formula refuses to link, and is reached through "brew
 # --prefix" instead), so the verification below is what actually decides.
-for formula in make dtc expect sdl2 bc p7zip dcfldd; do
+for formula in make dtc expect sdl2 bc p7zip dcfldd pkgconf portaudio; do
     brew link --overwrite "${formula}" > /dev/null 2>&1 || true
 done
 
 MISSING=
-for tool in dtc expect bc; do
+for tool in dtc expect bc pkg-config; do
     command -v "${tool}" > /dev/null || MISSING="${MISSING} ${tool}"
 done
 if [ -n "${MISSING}" ]; then

.ci/sound.sh

@@ -0,0 +1,153 @@
+#!/usr/bin/env bash
+
+# Get the directory of this script
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+. "${SCRIPT_DIR}/common.sh"
+
+check_platform
+
+# Overwrite the variable to use initrd rootfs when explicitly requested.
+SPECIFY_ROOTFS=${1:-}
+if [[ -n "${SPECIFY_ROOTFS}" && "${SPECIFY_ROOTFS}" != "initrd" ]]; then
+    print_error "Unsupported rootfs for virtio-snd test: ${SPECIFY_ROOTFS}"
+    exit 2
+fi
+if [[ "${SPECIFY_ROOTFS}" == "initrd" ]]; then
+    OPTS_BASE_ROOTFS_EXT4="${OPTS_BASE}"
+fi
+
+# Ensure a failed/timeout test does not leave rv32emu running.
+register_cleanup cleanup_emulator
+
+RET=0
+
+MESSAGES=(
+    "${COLOR_G}OK!"
+    "${COLOR_R}Fail to boot"
+    "${COLOR_R}Fail to login"
+    "${COLOR_R}Fail to bind virtio-snd driver"
+    "${COLOR_R}Fail to enumerate ALSA card"
+    "${COLOR_R}Fail to enumerate ALSA PCM device"
+    "${COLOR_R}Fail to play PCM with speaker-test"
+)
+
+# GitHub Actions runners do not provide a physical audio output device.
+# Use the ALSA null PCM as the default output so PortAudio can exercise
+# the virtio-snd playback path in headless CI.
+if [[ "${CI:-}" == "true" && "$(uname -s)" == "Linux" ]]; then
+    cat > "${HOME}/.asoundrc" << 'EOF'
+pcm.!default {
+    type null
+}
+EOF
+fi
+
+RUN_LINUX="build/rv32emu ${OPTS_BASE_ROOTFS_EXT4} -x vsnd"
+
+printf "${COLOR_Y}===== Test option: ${OPTS_BASE_ROOTFS_EXT4} -x vsnd =====${COLOR_N}\n"
+
+ASSERT expect <<- DONE
+	set timeout ${TIMEOUT}
+
+	spawn ${RUN_LINUX}
+
+	expect {
+	    "buildroot login:" {
+	        send "root\r"
+	    }
+	    timeout {
+	        exit 1
+	    }
+	}
+
+	expect {
+	    "# " {}
+	    timeout {
+	        exit 2
+	    }
+	}
+
+	send "readlink /sys/bus/virtio/devices/virtio0/driver\r"
+	expect {
+	    "virtio_snd" {}
+	    timeout {
+	        exit 3
+	    }
+	}
+
+	expect "# "
+	send "cat /proc/asound/cards\r"
+	expect {
+	    "VirtIO SoundCard" {}
+	    timeout {
+	        exit 4
+	    }
+	}
+
+	expect "# "
+	send "aplay -l\r"
+	expect {
+	    "VirtIO SoundCard" {}
+	    timeout {
+	        exit 5
+	    }
+	}
+
+	# Exercise the PCM playback path with a bounded single loop. Use an
+	# explicitly sized buffer to tolerate scheduling jitter on shared CI runners.
+	expect "# "
+	set timeout 60
+	send "speaker-test -D hw:0,0 -c 1 -r 48000 -F S16_LE -t sine -b 1200000 -p 300000 -P 4 -l 1; echo SPEAKER_TEST_RC:\\\$?\r"
+
+	expect {
+	    "Playback open error:" {
+	        exit 6
+	    }
+	    "Setting of hwparams failed:" {
+	        exit 6
+	    }
+	    "Setting of swparams failed:" {
+	        exit 6
+	    }
+	    "Transfer failed:" {
+	        exit 6
+	    }
+	    "0 - Mono" {}
+	    timeout {
+	        exit 6
+	    }
+	}
+
+	# One completed loop is sufficient to verify end-to-end PCM progress.
+	expect {
+	    "Time per period =" {}
+	    "Transfer failed:" {
+	        exit 6
+	    }
+	    timeout {
+	        exit 6
+	    }
+	}
+
+	expect {
+	    "SPEAKER_TEST_RC:0" {}
+	    -re {SPEAKER_TEST_RC:([1-9][0-9]*)} {
+	        exit 6
+	    }
+	    timeout {
+	        exit 6
+	    }
+	}
+
+	expect "# "
+	send "\x01"
+	send "x"
+DONE
+
+ret=$?
+RET=$((${RET} + ${ret}))
+cleanup
+
+printf "\nVirtio-snd Test: [ ${MESSAGES[$ret]}${COLOR_N} ]\n"
+
+exit ${RET}

.github/actions/setup-build/action.yml

@@ -57,8 +57,8 @@ runs:
       shell: bash
       run: |
         .ci/apt-install.sh curl wget lsb-release software-properties-common \
-            gnupg libsdl2-dev libsdl2-mixer-dev device-tree-compiler expect \
-            bc p7zip-full e2fsprogs
+            gnupg libsdl2-dev libsdl2-mixer-dev portaudio19-dev pkg-config \
+            device-tree-compiler expect bc p7zip-full e2fsprogs
 
     # No Homebrew cache on purpose. The cache can only carry the Cellar, not
     # the opt/ and bin/ symlinks, and "brew install" on a formula it already

Makefile

@@ -72,7 +72,7 @@ deps :=
 # Feature Flags (Kconfig -> RV32_FEATURE_*)
 $(call set-features, ELF_LOADER MOP_FUSION BLOCK_CHAINING LOG_COLOR)
 $(call set-features, SYSTEM GOLDFISH_RTC ARCH_TEST)
-$(call set-features, VIRTIO_NET VIRTIO_NET_TAP VIRTIO_NET_USER VIRTIO_NET_VMNET)
+$(call set-features, VIRTIO_NET VIRTIO_NET_TAP VIRTIO_NET_USER VIRTIO_NET_VMNET VIRTIO_SND)
 $(call set-features, EXT_M EXT_A EXT_F EXT_C EXT_V RV32E)
 $(call set-features, Zicsr Zifencei Zba Zbb Zbc Zbs)
 $(call set-features, SDL SDL_MIXER GDBSTUB JIT LINK_ZLIB ROOTFS_EXT4)
@@ -219,7 +219,7 @@ ifeq ($(CONFIG_JIT),y)
             $(error JIT only supports x86_64 and ARM64 platforms.)
         endif
     endif
-$(OUT)/jit.o: src/jit.c src/rv32_jit.c $(CONFIG_HEADER)
+$(OUT)/jit.o: src/jit.c src/rv32_jit.c $(CONFIG_HEADER) $(EFFECTIVE_CONFIG_STAMP)
 	$(VECHO) "  CC\t$@\n"
 	$(Q)$(CC) -o $@ $(CFLAGS) -c -MMD -MF $@.d $<
 # T2C optimization level from Kconfig (0-3, default 3)
@@ -240,6 +240,9 @@ include mk/http.mk
 # VirtIO networking
 include mk/virtio-net.mk
 
+# VirtIO sound
+include mk/virtio-snd.mk
+
 # External Dependencies & System Emulation
 include mk/external.mk
 include mk/artifact.mk
@@ -265,7 +268,7 @@ deps += $(OBJS:%.o=%.o.d)
 EFFECTIVE_CONFIG_VARS := \
 	CONFIG_BUILD_WASM CONFIG_SYSTEM CONFIG_GOLDFISH_RTC CONFIG_ELF_LOADER \
 	CONFIG_VIRTIO_NET CONFIG_VIRTIO_NET_TAP CONFIG_VIRTIO_NET_USER \
-	CONFIG_VIRTIO_NET_VMNET \
+	CONFIG_VIRTIO_NET_VMNET CONFIG_VIRTIO_SND CONFIG_HAVE_PORTAUDIO \
 	CONFIG_EXT_M CONFIG_EXT_A CONFIG_EXT_F CONFIG_EXT_C CONFIG_EXT_V CONFIG_RV32E \
 	CONFIG_Zicsr CONFIG_Zifencei CONFIG_Zba CONFIG_Zbb CONFIG_Zbc CONFIG_Zbs \
 	CONFIG_MOP_FUSION CONFIG_BLOCK_CHAINING CONFIG_LOG_COLOR CONFIG_ARCH_TEST \

README.md

@@ -88,6 +88,7 @@ button that switches directly to the other.
 | Prebuilt binaries | [docs/prebuilt.md](docs/prebuilt.md) |
 | Base image preparation | [docs/base-image.md](docs/base-image.md) |
 | Networking guidance | [docs/networking.md](docs/networking.md) |
+| Sound guidance | [docs/sound.md](docs/sound.md) |
 
 ## Contributing
 See [CONTRIBUTING.md](CONTRIBUTING.md) for contribution guidelines.

configs/Kconfig

@@ -99,6 +99,11 @@ config HAVE_RISCV_TOOLCHAIN
     bool
     default $(python,assert run(sys.executable, 'tools/detect-env.py', '--have-riscv-toolchain'))
 
+config HAVE_PORTAUDIO
+    bool
+    default n if CC_IS_EMCC
+    default $(python,assert run('pkg-config', '--exists', 'portaudio-2.0'))
+
 # Host platform detection used by platform-specific system devices.
 config HOST_LINUX
     def_bool $(python,assert sys.platform.startswith('linux'))
@@ -310,6 +315,23 @@ config ELF_LOADER
       Enable this for running 'make check' tests in system mode.
       Disable this for booting Linux kernel images.
 
+config VIRTIO_SND
+    bool "Enable VirtIO sound device"
+    default y
+    depends on SYSTEM && !ELF_LOADER && !CC_IS_EMCC
+    depends on HAVE_PORTAUDIO
+    help
+      Enable VirtIO sound device emulation for Linux system mode.
+
+      PCM playback is provided through PortAudio. The device can be
+      instantiated at runtime with the '-x vsnd' option.
+
+      Disable this option to exclude virtio-snd and its PortAudio
+      dependency from the rv32emu executable.
+
+comment "PortAudio not found - VirtIO sound support is unavailable"
+    depends on SYSTEM && !ELF_LOADER && !CC_IS_EMCC && !HAVE_PORTAUDIO
+
 config VIRTIO_NET
     bool "Enable VirtIO network device"
     default y

configs/system_defconfig

@@ -11,3 +11,4 @@ CONFIG_VIRTIO_NET_TAP=y
 CONFIG_VIRTIO_NET_USER=y
 CONFIG_VIRTIO_NET_VMNET=y
 CONFIG_ROOTFS_EXT4=y
+CONFIG_VIRTIO_SND=y

configs/system_interpreter_defconfig

@@ -8,3 +8,5 @@ CONFIG_VIRTIO_NET=y
 CONFIG_VIRTIO_NET_TAP=y
 CONFIG_VIRTIO_NET_USER=y
 CONFIG_VIRTIO_NET_VMNET=y
+CONFIG_VIRTIO_SND=y
+

docs/networking.md

@@ -62,14 +62,28 @@ where `<backend>` is one of the supported backend names for the current host.
 
 ### Linux TAP mode
 
-TAP mode requires root privileges or `CAP_NET_ADMIN`.
+TAP mode requires network administration privileges, which can be provided either by running rv32emu with `sudo` or by granting the executable `CAP_NET_ADMIN`.
 
-Start rv32emu:
+When TAP networking is used together with virtio-snd, prefer `CAP_NET_ADMIN` instead of running the whole emulator with `sudo`. PortAudio normally connects to the audio session of the logged-in desktop user, such as PipeWire or PulseAudio. Running rv32emu as root may prevent PortAudio from accessing that user session.
+
+Grant the required capability to the rv32emu executable:
+
+```shell
+sudo setcap cap_net_admin+ep build/rv32emu
+getcap build/rv32emu
+
+build/rv32emu \
+  -k build/linux-image/Image \
+  -x vblk:build/linux-image/rootfs.ext4,rootfs \
+  -x vnet:tap \
+  -x vsnd
+```
+If you just want to use virtio-net only (without virtio-snd), you can start rv32emu with `sudo -E`:
 
 ```shell
 sudo -E build/rv32emu \
   -k build/linux-image/Image \
-  -i build/linux-image/rootfs.cpio \
+  -x vblk:build/linux-image/rootfs.ext4,rootfs \
   -x vnet:tap
 ```
 
@@ -100,7 +114,7 @@ Start rv32emu:
 ```shell
 build/rv32emu \
   -k build/linux-image/Image \
-  -i build/linux-image/rootfs.cpio \
+  -x vblk:build/linux-image/rootfs.ext4,rootfs \
   -x vnet:user
 ```
 
@@ -125,7 +139,7 @@ mode through:
 ```shell
 sudo -E build/rv32emu \
   -k build/linux-image/Image \
-  -i build/linux-image/rootfs.cpio \
+  -x vblk:build/linux-image/rootfs.ext4,rootfs \
   -x vnet:vmnet
 ```
 
@@ -167,7 +181,7 @@ On macOS, use the user-mode SLIRP backend:
 ```shell
 build/rv32emu \
   -k build/linux-image/Image \
-  -i build/linux-image/rootfs.cpio \
+  -x vblk:build/linux-image/rootfs.ext4,rootfs \
   -x vnet:user
 ```