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fix: raise the container memlock limit so QEMU can set up io_uring #9

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Merged
vaggeliskls merged 1 commit into from
Oct 7, 2026
Merged

fix: raise the container memlock limit so QEMU can set up io_uring #9

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4 changes: 0 additions & 4 deletions .env.example
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Original file line number Diff line number Diff line change
Expand Up @@ -59,10 +59,6 @@ VERSION=2022
RAM_SIZE=8G
CPU_CORES=4
DISK_SIZE=100G
# QEMU disk I/O backend: native, threads or io_uring. Empty lets QEMU choose,
# which is io_uring on recent kernels. Kernels before 5.12 (Ubuntu 20.04) fail
# at boot with "Failed to initialize io_uring": set native there.
# DISK_IO=native
# Local administrator created by the unattended install; also the RDP login
WIN_USERNAME=admin
WIN_PASSWORD=runner
1 change: 0 additions & 1 deletion README.md
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Expand Up @@ -47,7 +47,6 @@ Two authentication methods are supported. Set **one** of them in `.env`:
| `INSTALL_RTOOLS` | `true` | Install Rtools 4.0 with `mingw-w64-x86_64-make` |
| `VERSION` | `2022` | dockur Windows release (`2022` = Windows Server 2022 evaluation) |
| `RAM_SIZE` / `CPU_CORES` / `DISK_SIZE` | `8G` / `4` / `100G` | VM size |
| `DISK_IO` | QEMU's choice | QEMU disk I/O backend: `native`, `threads` or `io_uring`. Kernels before 5.12 exit at boot with `Failed to initialize io_uring`; set `native` there |
| `WIN_USERNAME` / `WIN_PASSWORD` | `admin` / `runner` | Local administrator created by the install, also the RDP login |

2. Start it and follow the container side (ISO download, QEMU boot):
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12 changes: 9 additions & 3 deletions docker-compose.yml
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Expand Up @@ -17,16 +17,22 @@ services:
RAM_SIZE: "${RAM_SIZE:-8G}"
CPU_CORES: "${CPU_CORES:-4}"
DISK_SIZE: "${DISK_SIZE:-100G}"
# QEMU disk I/O backend; empty lets QEMU choose. Set DISK_IO=native in .env
# on kernels before 5.12 ("Failed to initialize io_uring" at boot).
DISK_IO: "${DISK_IO:-}"
USERNAME: "${WIN_USERNAME:-admin}"
PASSWORD: "${WIN_PASSWORD:-runner}"
devices:
- /dev/kvm
- /dev/net/tun
cap_add:
- NET_ADMIN
# QEMU 10.1+ uses io_uring for its event loop and, on recent kernels, for the
# disk. io_uring rings are locked memory, and the container default of a few
# hundred KB makes QEMU exit at boot with "Failed to initialize io_uring:
# Cannot allocate memory". Unlimited is what the QEMU and Elasticsearch
# docs recommend; it is not a privilege.
ulimits:
memlock:
soft: -1
hard: -1
ports:
- 8006:8006 # web console (noVNC), handy during the first install
- 3389:3389/tcp # RDP
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