Audio passthrough example

examples/audio/Makefile

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+#
+# Copyright 2021, Breakaway Consulting Pty. Ltd.
+# Copyright 2022, UNSW (ABN 57 195 873 179)
+#
+# SPDX-License-Identifier: BSD-2-Clause
+#
+
+ifeq ($(strip $(MICROKIT_SDK)),)
+$(error MICROKIT_SDK must be specified)
+endif
+
+ifeq ($(strip $(BOARD)),)
+$(error BOARD must be specified)
+endif
+
+# Default build directory, pass BUILD_DIR=<dir> to override
+BUILD_DIR ?= build
+# Default config is a debug build, pass CONFIG=<debug/release/benchmark> to override
+CONFIG ?= debug
+
+# @ivanv: Check for dependencies and make sure they are installed/in the path
+
+# @ivanv: check that all dependencies exist
+# Specify that we use bash for all shell commands
+SHELL=/bin/bash
+# All dependencies needed to compile the VMM
+QEMU := qemu-system-aarch64
+QEMU_SND_BACKEND := pipewire
+DTC := dtc
+
+# ifndef TOOLCHAIN
+# 	# Get whether the common toolchain triples exist
+# 	TOOLCHAIN_AARCH64_LINUX_GNU := $(shell command -v aarch64-linux-gnu-gcc 2> /dev/null)
+# 	TOOLCHAIN_AARCH64_UNKNOWN_LINUX_GNU := $(shell command -v aarch64-unknown-linux-gnu-gcc 2> /dev/null)
+# 	# Then check if they are defined and select the appropriate one
+# 	ifdef TOOLCHAIN_AARCH64_LINUX_GNU
+# 		TOOLCHAIN := aarch64-linux-gnu
+# 	else ifdef TOOLCHAIN_AARCH64_UNKNOWN_LINUX_GNU
+# 		TOOLCHAIN := aarch64-unknown-linux-gnu
+# 	else
+# 		$(error "Could not find an AArch64 cross-compiler")
+# 	endif
+# endif
+
+CC := clang
+LD := ld.lld
+MICROKIT_TOOL ?= $(MICROKIT_SDK)/bin/microkit
+
+# @ivanv: need to have a step for putting in the initrd node into the DTB,
+# 		  right now it is unfortunately hard-coded.
+
+# @ivanv: check that the path of SDK_PATH/BOARD exists
+# @ivanv: Have a list of supported boards to check with, if it's not one of those
+# have a helpful message that lists all the support boards.
+
+# @ivanv: incremental builds don't work with IMAGE_DIR changing
+
+BOARD_DIR := $(MICROKIT_SDK)/board/$(BOARD)/$(CONFIG)
+VMM := ../../
+VMM_TOOLS := $(VMM)/tools
+VMM_SRC_DIR := $(VMM)/src
+SYSTEM_DESCRIPTION := board/$(BOARD)/audio.system
+
+IMAGE_DIR := board/$(BOARD)
+LINUX := $(IMAGE_DIR)/linux
+DTS := $(IMAGE_DIR)/linux.dts
+DTB := $(BUILD_DIR)/linux.dtb
+INITRD := $(IMAGE_DIR)/rootfs.cpio.gz
+
+ELFS := vmm.elf
+
+IMAGE_FILE = $(BUILD_DIR)/loader.img
+REPORT_FILE = $(BUILD_DIR)/report.txt
+
+# @ivanv: should only compile printf.o in debug
+VMM_OBJS := vmm.o printf.o virq.o linux.o guest.o psci.o smc.o fault.o util.o vgic.o vgic_v2.o package_guest_images.o tcb.o vcpu.o
+
+# Toolchain flags
+# FIXME: For optimisation we should consider providing the flag -mcpu.
+# FIXME: We should also consider whether -mgeneral-regs-only should be
+# used to avoid the use of the FPU and therefore seL4 does not have to
+# context switch the FPU.
+# Note we only need -Wno-unused-command-line-argument because in Nix
+# passes an extra `--gcc-toolchain` flag which we do not need.
+CFLAGS := -mstrict-align \
+		  -g3 \
+		  -O3 \
+		  -ffreestanding \
+		  -nostdlib \
+		  -Wno-unused-command-line-argument \
+		  -Wall -Wno-unused-function -Werror \
+		  -I$(VMM_SRC_DIR)/arch/aarch64 -I$(VMM_SRC_DIR) -I$(VMM_SRC_DIR)/util -I$(BOARD_DIR)/include \
+		  -DBOARD_$(BOARD) \
+		  -DCONFIG_$(CONFIG) \
+		  -target aarch64-none-elf
+
+LDFLAGS := -L$(BOARD_DIR)/lib
+LIBS := -lmicrokit -Tmicrokit.ld
+
+all: directories $(IMAGE_FILE)
+
+qemu: all
+	if ! command -v $(QEMU) &> /dev/null; then echo "Could not find dependency: qemu-system-aarch64"; exit 1; fi
+	$(QEMU) -machine virt,virtualization=on,secure=off \
+			-cpu cortex-a53 \
+			-serial mon:stdio \
+			-device loader,file=$(IMAGE_FILE),addr=0x70000000,cpu-num=0 \
+			-audio driver=$(QEMU_SND_BACKEND),model=hda,id=$(QEMU_SND_BACKEND) \
+			-m size=2G \
+			-nographic
+
+directories:
+	$(shell mkdir -p $(BUILD_DIR))
+
+$(DTB): $(DTS)
+	if ! command -v $(DTC) &> /dev/null; then echo "Could not find dependency: Device Tree Compiler (dtc)"; exit 1; fi
+	# @ivanv: Shouldn't supress warnings
+	$(DTC) -q -I dts -O dtb $< > $@
+
+$(BUILD_DIR)/package_guest_images.o: $(VMM_TOOLS)/package_guest_images.S $(IMAGE_DIR) $(LINUX) $(INITRD) $(DTB)
+	$(CC) -c -g3 -x assembler-with-cpp \
+					-DGUEST_KERNEL_IMAGE_PATH=\"$(LINUX)\" \
+					-DGUEST_DTB_IMAGE_PATH=\"$(DTB)\" \
+					-DGUEST_INITRD_IMAGE_PATH=\"$(INITRD)\" \
+					-target aarch64-none-elf \
+					$< -o $@
+
+$(BUILD_DIR)/%.o: %.c Makefile
+	$(CC) -c $(CFLAGS) $< -o $@
+
+$(BUILD_DIR)/%.o: $(VMM_SRC_DIR)/%.c Makefile
+	$(CC) -c $(CFLAGS) $< -o $@
+
+$(BUILD_DIR)/%.o: $(VMM_SRC_DIR)/util/%.c Makefile
+	$(CC) -c $(CFLAGS) $< -o $@
+
+$(BUILD_DIR)/%.o: $(VMM_SRC_DIR)/arch/aarch64/%.c Makefile
+	$(CC) -c $(CFLAGS) $< -o $@
+
+$(BUILD_DIR)/%.o: $(VMM_SRC_DIR)/arch/aarch64/vgic/%.c Makefile
+	$(CC) -c $(CFLAGS) $< -o $@
+
+$(BUILD_DIR)/vmm.elf: $(addprefix $(BUILD_DIR)/, $(VMM_OBJS))
+	$(LD) $(LDFLAGS) $^ $(LIBS) -o $@
+
+$(IMAGE_FILE) $(REPORT_FILE): $(addprefix $(BUILD_DIR)/, $(ELFS)) $(SYSTEM_DESCRIPTION) $(IMAGE_DIR)
+	$(MICROKIT_TOOL) $(SYSTEM_DESCRIPTION) --search-path $(BUILD_DIR) $(IMAGE_DIR) --board $(BOARD) --config $(CONFIG) -o $(IMAGE_FILE) -r $(REPORT_FILE)

examples/audio/README.md

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+# A VMM example for pass-through audio in Linux
+
+This example is a minimal VMM that supports Linux guests and a basic
+buildroot/BusyBox root file system. This gives a basic command-line with some
+common Linux utilities.
+
+The example currently works on the following platforms:
+* QEMU ARM virt
+
+## Building with Make
+
+```sh
+make BOARD=<BOARD> MICROKIT_SDK=/path/to/sdk
+```
+
+Where `<BOARD>` is one of:
+* `qemu_arm_virt`
+* `odroidc4`
+
+Other configuration options can be passed to the Makefile such as `CONFIG`
+and `BUILD_DIR`, see the Makefile for details.
+
+If you would like to simulate the QEMU board you can run the following command:
+```sh
+make BOARD=qemu_arm_virt MICROKIT_SDK=/path/to/sdk qemu
+```
+
+This will build the example code as well as run the QEMU command to simulate a
+system running the whole system.
+
+
+## Playing audio
+
+Guest username is `root`.
+```
+alsactl init -U
+play CantinaBand3.wav
+```

examples/audio/board/odroidc4/audio.system

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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+ Copyright 2022, UNSW (ABN 57 195 873 179)
+
+ SPDX-License-Identifier: BSD-2-Clause
+-->
+<system>
+    <!-- We allocate 256MiB of RAM for the guest. -->
+    <memory_region name="guest_ram" size="0x10_000_000" phys_addr="0x20000000" page_size="0x200_000" />
+    <memory_region name="bus1" size="0x200000" phys_addr="0xff600000" />
+    <memory_region name="bus2" size="0x200000" phys_addr="0xff800000" />
+    <memory_region name="bus3" size="0x100000" phys_addr="0xffd00000" />
+    <memory_region name="gic_vcpu" size="0x1_000" phys_addr="0xffc06000" />
+
+    <memory_region name="usb_ctrl" size="0x1_000" phys_addr="0xffe09000" />
+    <memory_region name="usb_1" size="0x40000" phys_addr="0xff400000" />
+    <memory_region name="usb_2" size="0x100000" phys_addr="0xff500000" />
+
+    <protection_domain name="VMM" priority="254">
+        <program_image path="vmm.elf" />
+        <map mr="guest_ram" vaddr="0x20000000" perms="rw" setvar_vaddr="guest_ram_vaddr" />
+        <virtual_machine name="linux" id="0">
+            <map mr="guest_ram" vaddr="0x20000000" perms="rwx" />
+            <map mr="bus1" vaddr="0xff600000" perms="rw" cached="false" />
+            <map mr="bus2" vaddr="0xff800000" perms="rw" cached="false" />
+            <map mr="bus3" vaddr="0xffd00000" perms="rw" cached="false" />
+            <map mr="gic_vcpu" vaddr="0xffc02000" perms="rw" cached="false" />
+
+            <map mr="usb_ctrl" vaddr="0xffe09000" perms="rw" cached="false" />
+            <map mr="usb_1" vaddr="0xff400000" perms="rw" cached="false" />
+            <map mr="usb_2" vaddr="0xff500000" perms="rw" cached="false" />
+
+        </virtual_machine>
+        <!-- Serial IRQ -->
+        <irq irq="225" id="1" trigger="edge" />
+
+        <!-- USB -->
+        <irq irq="48" id="2" trigger="level" /> <!-- Controller -->
+        <irq irq="63" id="3" trigger="level" /> <!-- USB 1 -->
+        <irq irq="62" id="4" trigger="level" /> <!-- USB 2 -->
+
+        <!-- @alexbr: not sure what this is -->
+        <irq irq="5" id="5" trigger="level" />
+
+    </protection_domain>
+</system>
+