Ubuntu 26.04 LTS guest end-to-end:
- cidata-driven autoinstall pipeline (subiquity user-data + nested
cloud-init bootcmd) in disk_util.c. Static NAT IP, ssh-via-vsock
marker, serial-debug kernel cmdline injected into ESP grub.cfg by
iso-patch.exe. Five separate firstboot pipeline fixes get the VM
to GDM unattended on Hyper-V Gen 2.
- Linux guest stack under tools/linux/:
- appsandbox-agent (vsock :1 control + clipboard helper spawn)
- appsandbox-audio (snd-aloop -> vsock :4)
- appsandbox-display (KMS framebuffer capture -> vsock :2)
- appsandbox-input (uinput injection <- vsock :3)
- appsandbox-clipboard (XCB selection bridge <-> vsock :5/:6)
Helper binaries staged via release/resources/linux/.
- asb_drm DRM module: virtual single-CRTC display sink the host
captures over vsock. Platform-bus, DRIVER_GEM/MODESET/ATOMIC/RENDER,
linear shmem framebuffers. asb-evict-simpledrm.service unbinds the
EFI simple-framebuffer before display-manager so mutter binds
asb_drm as the sole DRM card.
- dxgkrnl vendored byte-identical from microsoft/WSL2-Linux-Kernel
linux-msft-wsl-6.18.y with our DKMS/out-of-tree shim (dxgkrnl_compat.h
+ Kbuild + dkms.conf). Autoinstall late-commands dkms-builds against
every /target/lib/modules/<kver> so kernel-version drift between ISO
and post-update reboot still leaves a working .ko.
- wsl-mesa custom build (Mesa 25.3 + d3d12 gallium + microsoft-
experimental dzn Vulkan). Installs to /opt/wsl-mesa parallel to
Ubuntu's stock Mesa. Prebuilt tarball for ubuntu-26.04-amd64
shipped under tools/linux/wsl-mesa/prebuilt/ (21 MB).
- Per-VM GPU acceleration policy:
- /etc/systemd/user-environment-generators/50-appsandbox-gpu
emits GALLIUM_DRIVER=d3d12 + LD_LIBRARY_PATH + VK_DRIVER_FILES
into the user@1000 systemd-user environment when /dev/dxg and
/opt/wsl-mesa are present. Inherited by every app-*.scope a
.desktop launch creates.
- /etc/systemd/user/org.gnome.Shell@.service.d/no-gpu.conf
UnsetEnvironment= strips these for the compositor — mutter
stays on llvmpipe so asb_drm scanout works (the d3d12 pipe has
no GBM compatibility with asb_drm).
- /usr/local/bin/appsandbox-gpu wrapper for terminal-launched
opt-in GPU acceleration (probes /dev/dxg; no-op on no-GPU VMs).
- Host changes:
- vm_display_idd.c, vm_clipboard.c, vm_agent.c, vm_ssh_proxy.c,
asb_display.c: hcs_service_guid(os_type, port) so the same code
paths reach the per-OS service identifiers (HV_GUID for Windows,
vsock template for Linux).
- asb_core.c: linux_create_thread builds an empty VHDX, cidata
ISO with extras (agent ELFs, dxgkrnl src, asb_drm src, wsl-mesa
tarball, wsl-deps libs), and boots the desktop ISO + cidata.
- hcs_vm.c: HostLxssLib Plan9 share appended for Linux VMs;
VideoMonitor + ComPorts retained for serial debug.
- gpu_enum.c/h: gpu_append_lxsslib_share helper.
- vm_clipboard.c file-drop support (CF_HDROP / x-special/gnome-
copied-files round-trip).
- vm_display_idd.c: 32-bit S32_LE PCM audio path matches the
Linux daemon's snd-aloop capture format.
- iso-patch.c gains a patch_ubuntu_esp_grub_for_debug pass that
rewrites /EFI/ubuntu/grub.cfg via the FAT32 ESP, plus a qcow2->
vhdx converter with a RFC 1951 DEFLATE inflater for compressed
cluster handling.
- wsl-deps: Microsoft's libd3d12.so / libd3d12core.so / libdxcore.so
fetched on demand from the public NuGet feed
pkgs.dev.azure.com/shine-oss/wsl (no auth). Staged at
/opt/appsandbox/wsl-deps on the guest and put on /etc/ld.so.conf.d
rather than /usr/lib/wsl/lib (which is overlaid by the agent's
9P mount).
UI: web/{app.js,index.html} expose Linux VM creation + GPU selection,
distribution dropdown for cached Ubuntu ISOs, and the ISO picker for
custom images.
4.9 KiB
tools/linux — Linux-side build of AppSandbox guest components
Everything in this tree compiles on a Linux box and produces artifacts that the Windows AppSandbox host needs in order to stage a Linux VM. The components:
| Subdir | What it builds | Where it ends up in the guest |
|---|---|---|
agent/ |
5 userspace daemons (ELF) | /usr/local/bin/appsandbox-{agent,audio,clipboard,display,input} |
dxgkrnl/ |
Hyper-V GPU paravirt kernel module | /lib/modules/<kver>/updates/dxgkrnl.ko (or DKMS) |
asb_drm/ |
Stub DRM driver for KMS capture | /lib/modules/<kver>/updates/asb_drm.ko (or DKMS) |
wsl-mesa/ |
(optional) Mesa with d3d12 + dzn | tarball extracted to /opt/wsl-mesa/ |
wsl-deps/ (Microsoft's proprietary libd3d12.so etc.) is not built
here — it's fetched by the Windows host from Microsoft's public NuGet feed
into C:\ProgramData\AppSandbox\wsl-deps\. See tools/wsl-deps/README.md.
Build
Prereqs (Ubuntu 26.04+; package names may differ on other distros):
sudo apt-get install -y \
build-essential dkms zstd \
linux-headers-$(uname -r) \
libdrm-dev libasound2-dev libxcb1-dev libxcb-xfixes0-dev
Then from this directory:
make
That builds the 5 daemons, both kernel modules against your running kernel,
and installs them under tools/linux/dist/:
tools/linux/dist/
├── appsandbox-agent ← strip'd ELF
├── appsandbox-audio
├── appsandbox-clipboard
├── appsandbox-display
├── appsandbox-input
└── modules/
└── <uname-r>/
├── dxgkrnl.ko
└── asb_drm.ko
dist/ is gitignored — it's only valid on this machine for this kernel.
Other targets:
| Target | What it does |
|---|---|
make compile |
builds in place but doesn't copy to dist/ |
make agents |
builds only the userspace daemons |
make modules |
builds only the kernel modules |
make clean |
removes *.o, *.ko, daemon ELFs from source dirs |
make distclean |
clean + removes dist/ |
Transfer to the Windows host
This step is manual on purpose — there's no assumption of network connectivity between your Linux build box and the Windows machine that runs AppSandbox.
After a successful build, get dist/'s contents over to your Windows host
and place them at:
<appsandbox-repo>\release\resources\linux\
The simplest approach is a tarball:
tar -C dist -czf ~/asb-linux.tar.gz .
Then transfer asb-linux.tar.gz to the Windows host by whatever means you
normally use to move files between these two systems (USB stick, shared
filesystem, file-share VM, scp, manual upload — whatever works for your
setup). On the Windows side, in your appsandbox checkout:
mkdir release\resources\linux
tar xzf C:\path\to\asb-linux.tar.gz -C release\resources\linux\
tar.exe ships with Windows 10+; if it isn't on your PATH the Git for
Windows / 7-Zip / WinRAR equivalents all handle .tar.gz fine.
How the staged files reach a running VM
release/resources/linux/is a committed staging dir on the Windows side — same model as the existingrelease/resources/appsandbox-*.exefiles used for Windows guests.AppSandbox.vcxproj's PostBuildEvent xcopiesrelease/resources/intobin/<cfg>/resources/next toAppSandbox.exeandAppSandboxCore.dll. That happens on every build, so a rebuild after copying the new files makes them runtime-visible.- When you create a Linux VM,
disk_util.c::iso_create_resources_ubuntubuilds acidata.isowithuser-data(autoinstall) + anextras/tree that includes everything from<exe_dir>/resources/linux/. - On first boot of the VM, autoinstall mounts the cidata ISO, copies
extras/into/opt/appsandbox/, then runssetup.shviacurtin in-target.setup.shinstalls the agent ELFs into/usr/local/bin/, the kernel modules into/lib/modules/<kver>/updates/, wires up systemd units, and enables them.
Kernel module version skew
Kernel modules built here only load against an identical kernel version
in the guest (uname -r must match exactly). If the guest is on a different
kernel from your build machine, setup.sh automatically falls back to the
DKMS build path — it copies the source from extras/dxgkrnl/src/ to
/usr/src/dxgkrnl-<ver>/ and runs dkms install. DKMS handles future
kernel upgrades automatically. The committed .ko is just a fast path.