Hello world application in Web Assembly

setup.sh

@@ -2,6 +2,7 @@
 
 test -d repos/unikraft || git clone https://github.com/unikraft/unikraft repos/unikraft
 test -d repos/libs/musl || git clone https://github.com/unikraft/lib-musl repos/libs/musl
+test -d repos/libs/musl || git clone https://github.com/unikraft/lib-wamr repos/libs/wamr
 test -d repos/libs/lwip || git clone https://github.com/unikraft/lib-lwip repos/libs/lwip
 test -d repos/libs/libcxx || git clone https://github.com/unikraft/lib-libcxx repos/libs/libcxx
 test -d repos/libs/libcxxabi || git clone https://github.com/unikraft/lib-libcxxabi repos/libs/libcxxabi

wasm-hello/.gitignore

@@ -0,0 +1 @@
+/workdir/

wasm-hello/Config.uk

@@ -0,0 +1,10 @@
+# Configure WASM Hello application
+config APPWASMHELLO
+    bool "WASM Hello World Application"
+    default y
+    select LIBWAMR
+    select CONFIG_LIBWAMR_MAIN_FUNCTION
+    select LIBUKDEBUG
+    select LIBUKLIBPARAM
+    select LIBMUSL
+    select LIBLWIP

wasm-hello/Makefile

@@ -0,0 +1,10 @@
+UK_ROOT ?= $(PWD)/workdir/unikraft
+UK_LIBS ?= $(PWD)/workdir/libs
+UK_BUILD ?= $(PWD)/workdir/build
+LIBS := $(UK_LIBS)/musl:$(UK_LIBS)/lwip:$(UK_LIBS)/wamr
+
+all:
+	@$(MAKE) -C $(UK_ROOT) A=$(PWD) L=$(LIBS) O=$(UK_BUILD)
+
+$(MAKECMDGOALS):
+	@$(MAKE) -C $(UK_ROOT) A=$(PWD) L=$(LIBS) O=$(UK_BUILD) $(MAKECMDGOALS)

wasm-hello/Makefile.uk

@@ -0,0 +1,4 @@
+$(eval $(call addlib,appwasmhello))
+
+
+APPWASMHELLO_WASM-y += $(APPWASMHELLO_BASE)/main.wasm

wasm-hello/README.md

@@ -0,0 +1,284 @@
+# WASM Hello World on Unikraft
+
+Build and run a WebAssembly (Wasm) hello world program on Unikraft.
+This program runs inside an iwasm Intel runtime environment, which is a lightweight WebAssembly runtime designed for efficient execution of WebAssembly modules.
+Follow the instructions below to set up, configure, build and run the program.
+Make sure you installed the [requirements](../README.md#requirements).
+
+## Quick Setup (aka TLDR)
+
+For a quick setup, run the commands below.
+Note that you still need to install the [requirements](../README.md#requirements).
+Before everything, make sure you run the [top-level `setup.sh` script](../setup.sh).
+
+To build and run the application for `x86_64`, use the commands below:
+
+```console
+./setup.sh
+make distclean
+wget -O /tmp/defconfig https://raw.githubusercontent.com/unikraft/catalog-core/refs/heads/scripts/wasm-hello/scripts/defconfig/qemu.x86_64
+UK_DEFCONFIG=/tmp/defconfig make defconfig
+make -j $(nproc)
+rm -f initrd.cpio
+./workdir/unikraft/support/scripts/mkcpio initrd.cpio ./rootfs/
+qemu-system-x86_64 \
+    -nographic \
+    -m 16 \
+    -cpu max \
+    -kernel workdir/build/wasm-hello_qemu-x86_64 \
+    -append "wasm-hello_qemu-x86_64 vfs.fstab=[ \"initrd0:/:extract::ramfs=1:\" ] -- main.wasm" \
+    -initrd ./initrd.cpio
+```
+
+This will configure, build and run the application, resulting in a
+
+```text
+Hello world!
+buf ptr: 0x400002b0
+buf: 1234
+```
+
+message being printed.
+
+To do the same for `AArch64`, run the commands below:
+
+```console
+./setup.sh
+make distclean
+wget -O /tmp/defconfig https://raw.githubusercontent.com/unikraft/catalog-core/refs/heads/scripts/wasm-hello/scripts/defconfig/qemu.arm64
+UK_DEFCONFIG=/tmp/defconfig make defconfig
+make -j $(nproc)
+rm -f initrd.cpio
+./workdir/unikraft/support/scripts/mkcpio initrd.cpio ./rootfs/
+qemu-system-aarch64 \
+    -nographic \
+    -machine virt \
+    -m 32 \
+    -cpu max \
+    -kernel workdir/build/wasm-hello_qemu-arm64 \
+    -append "wasm-hello_qemu-arm64 vfs.fstab=[ \"initrd0:/:extract::ramfs=1:\" ] -- hello.wasm" \
+    -initrd ./initrd.cpio
+```
+
+Similar to the `x86_64` build, this will result in a
+
+```text
+Powered by
+o.   .o       _ _               __ _
+Oo   Oo  ___ (_) | __ __  __ _ ' _) :_
+oO   oO ' _ `| | |/ /  _)' _` | |_|  _)
+oOo oOO| | | | |   (| | | (_) |  _) :_
+ OoOoO ._, ._:_:_,\_._,  .__,_:_, \___)
+                          Helene 0.18.0
+Hello world!
+buf ptr: 0x400002b0
+buf: 1234
+```
+
+Information about every step and about other types of builds is detailed below.
+
+## Set Up
+
+Set up the required repositories.
+For this, you have two options:
+
+1. Use the `setup.sh` script:
+
+   ```console
+   ./setup.sh
+   ```
+
+   It will create symbolic links to the required repositories in `../repos/`.
+   Be sure to run the [top-level `setup.sh` script](../setup.sh).
+
+   If you want use a custom variant of repositories (e.g. apply your own patch, make modifications), update it accordingly in the `../repos/` directory.
+
+1. Have your custom setup of repositories in the `workdir/` directory.
+   Clone, update and customize repositories to your own needs.
+
+## Clean
+
+While not strictly required, it is safest to clean the previous build artifacts:
+
+```console
+make distclean
+```
+
+## Configure
+
+To configure the kernel, use:
+
+```console
+make menuconfig
+```
+
+In the console menu interface, choose the target architecture (x86_64 or ARMv8 or ARMv7) and platform (Xen or KVM/QEMU or KVM/Firecracker).
+
+The end result will be the creation of the `.config` configuration file.
+
+## Build
+
+Build the application for the current configuration:
+
+```console
+make -j $(nproc)
+```
+
+This results in the creation of the `workdir/build/` directory storing the build artifacts.
+The unikernel application image file is `workdir/build/wasm-hello_<plat>-<arch>`, where `<plat>` is the platform name (`qemu`, `fc`, `xen`), and `<arch>` is the architecture (`x86_64` or `arm64`).
+
+```console
+$(nproc)
+```
+
+this uses all availble cpu cores to run the build process.
+
+### Build the Filesystem
+
+The filesystem is to be packed into `initrd.cpio`, an initial ramdisk CPIO file.
+Use the command below for that:
+
+```console
+rm -f initrd.cpio
+./workdir/unikraft/support/scripts/mkcpio initrd.cpio ./rootfs/
+```
+
+## Run
+
+Run the resulting image using the corresponding platform tool.
+Firecracker requires KVM support.
+
+Xen requires a system with Xen installed.
+
+A successful run will show a message such as the one below:
+
+```text
+Booting from ROM..Powered by
+o.   .o       _ _               __ _
+Oo   Oo  ___ (_) | __ __  __ _ ' _) :_
+oO   oO ' _ `| | |/ /  _)' _` | |_|  _)
+oOo oOO| | | | |   (| | | (_) |  _) :_
+ OoOoO ._, ._:_:_,\_._,  .__,_:_, \___)
+                          Helene 0.18.0
+Hello world!
+buf ptr: 0x400002b0
+buf: 1234
+```
+
+### Run on QEMU/x86_64
+
+```console
+qemu-system-x86_64 \
+    -nographic \
+    -m 16 \
+    -cpu max \
+    -kernel workdir/build/wasm-hello-x86_64 \
+    -append "wasm-hello-x86_64 vfs.fstab=[ \"initrd0:/:extract::ramfs=1:\" ] -- main.wasm" \
+    -initrd ./initrd.cpio
+```
+
+### Run on QEMU/ARM64
+
+```console
+qemu-system-aarch64 \
+    -nographic \
+    -machine virt \
+    -m 16 \
+    -cpu max \
+    -kernel workdir/build/wasm-hello-arm64 \
+    -append "wasm-hello-x86_64 vfs.fstab=[ \"initrd0:/:extract::ramfs=1:\" ] -- main.wasm" \
+    -initrd ./initrd.cpio
+```
+
+### Run on Firecracker/x86_64
+
+To run with firecraker use this command. this is run with debugging in mind. Feel free to run without it.
+
+the command below is used for dedugging perposes, feel free to omit.
+
+```console
+rm -f /tmp/firecracker.log
+> /tmp/firecracker.log
+```
+
+```console
+rm -f /tmp/firecracker.socket
+firecracker-x86_64 \
+        --api-sock /tmp/firecracker.socket \
+        --config-file ./fc.x86_64.json
+```
+
+The user running the above command must be able to use KVM.
+Typically this means being part of the `kvm` group.
+Otherwise, run the command above as root or prefixed by `sudo`.
+
+### Run on Firecracker/ARM64
+
+the command below is used for dedugging perposes, feel free to omit.
+
+```console
+rm -f /tmp/firecracker.log
+> /tmp/firecracker.log
+```
+
+```console
+rm -f firecracker.socket
+firecracker-aarch64 --config-file fc.arm64.json --api-sock firecracker.socket
+```
+
+The user running the above command must be able to use KVM.
+Typically this means being part of the `kvm` group.
+Otherwise, run the command above as the `root` account or prefixed by `sudo`.
+
+### Run on Xen/x86_64
+
+```console
+sudo xl create -c xen.x86_64.cfg
+```
+
+You need use `sudo` or the `root` account to run Xen.
+
+### Run on Xen/ARM64
+
+```console
+sudo xl create -c xen.arm64.cfg
+```
+
+You need use `sudo` or the `root` account to run Xen.
+
+## Clean Up
+
+Doing a new configuration, or a new build may require cleaning up the configuration and build artifacts.
+
+In order to remove the build artifacts, use:
+
+```console
+make clean
+```
+
+In order to remove fetched files also, that is the removal of the `workdir/build/` directory, use:
+
+```console
+make properclean
+```
+
+In order to remove the generated `.config` file as well, use:
+
+```console
+make distclean
+```
+
+## Customize
+
+WASM Hello is the simplest application to be run with Unikraft in web assembly.
+
+### Update the Unikraft Core Code
+
+If updating the Unikraft core code in the `./workdir/unikraft/` directory, you then go through the [configure](#configure), [build](#build) and [run](#run) steps.
+
+### Enable Debug Messages
+
+You can customize the ELF Loader build debug messages.
+For that, use the ["Configure" step](#configure) to add debug printing option from the [`ukdebug` library](https://github.com/unikraft/unikraft/tree/staging/lib/ukdebug).
+Then, build and run again.
+You can also enable debug configurations in `/tmp/defconfig`

wasm-hello/fc.arm64.json

@@ -0,0 +1,26 @@
+{
+  "boot-source": {
+    "kernel_image_path": "workdir/build/wasm-hello_fc-arm64",
+    "boot_args": "wasm-hello_qemu-x86_64 vfs.fstab=[ \"initrd0:/:extract::ramfs=1:\" ] -- main.wasm",
+    "initrd_path": "initrd.cpio"
+  },
+  "drives": [],
+  "machine-config": {
+    "vcpu_count": 1,
+    "mem_size_mib": 32,
+    "smt": false,
+    "track_dirty_pages": false
+  },
+  "cpu-config": null,
+  "balloon": null,
+  "vsock": null,
+  "logger": {
+    "log_path": "/tmp/firecracker.log",
+    "level": "Debug",
+    "show_level": true,
+    "show_log_origin": true
+  },
+  "metrics": null,
+  "mmds-config": null,
+  "entropy": null
+}

wasm-hello/fc.x86_64.json

@@ -0,0 +1,26 @@
+{
+  "boot-source": {
+    "kernel_image_path": "workdir/build/wasm-hello_fc-x86_64",
+    "boot_args": "wasm-hello_qemu-x86_64 vfs.fstab=[ \"initrd0:/:extract::ramfs=1:\" ] -- /main.wasm",
+    "initrd_path": "initrd.cpio"
+  },
+  "drives": [],
+  "machine-config": {
+    "vcpu_count": 1,
+    "mem_size_mib": 32,
+    "smt": false,
+    "track_dirty_pages": false
+  },
+  "cpu-config": null,
+  "balloon": null,
+  "vsock": null,
+  "logger": {
+    "log_path": "/tmp/firecracker.log",
+    "level": "Debug",
+    "show_level": true,
+    "show_log_origin": true
+  },
+  "metrics": null,
+  "mmds-config": null,
+  "entropy": null
+}