---
name: "sbuild-qemu"
section: "1"
platform: "linux"
package: "sbuild-qemu"
version: "0.89.3+deb13u4"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/sbuild-qemu"
---

# sbuild-qemu(1)

sbuild using QEMU images

## NAME

sbuild-qemu - sbuild using QEMU images

## SYNOPSIS

**sbuild-qemu** \[**-h**\] \[**--image=IMAGE**\] \[**--ram-size=MiB**\] \[**--cpus=CPUs**\] \[**--overlay-dir=OVERLAY\_DIR**\] \[**--noexec**\] \[**--autopkgtest-debug**\] \[**\<sbuild-options\>**\]

Build Debian packages with **sbuild** using QEMU images, by using sbuild's **--chroot-mode=autopkgtest**.

All options other than the ones described below are passed on through to [**sbuild**(1)](/sbuild/1.md), though the options **--dist**, **--arch** and **--build** are peeked at when looking for images. The image will be started in **-snapshot** mode, so the image is never modified. Multiple processes can use the same image concurrently.

## OPTIONS

- **-h**, **--help**

  Show this help message and exit.

- **--image**=IMAGE

  QEMU image file to use for building. If not specified, sbuild-qemu will look for an image with the name **DIST-autopkgtest-ARCH.img**, where DIST is taken from **--dist** if present, and ARCH is taken from **--arch** or **--build** if present. Otherwise, DIST defaults to 'unstable', and ARCH to the host architecture. sbuild-qemu will first look in the current directory for such an image, and then in the directory **$IMAGEDIR**. A suitable image can be created with [sbuild-qemu-create(1)](/sbuild-qemu-create/1.md).

- **--ram-size**=MiB

  VM memory size in MB. Default: 2048

- **--cpus**=CPUs

  VM CPU count. Default: 2

- **--overlay-dir**=OVERLAY\_DIR

  Directory for the temporary image overlay instead of autopkgtest's default of */tmp* (or $TMPDIR).

- **--noexec**

  Don't actually do anything. Just print the [sbuild(1)](/sbuild/1.md) command string that would be executed, and then exit.

- **--autopkgtest-debug**

  Enable debug output for the [autopkgtest-virt-qemu(1)](/autopkgtest-virt-qemu/1.md) driver.

- **--boot**=auto,bios,efi,ieee1275,none

  How to boot the image. Default is BIOS on amd64 and i386, EFI on arm64 and armhf, and IEEE1275 on ppc64el.

## CONSIDERATIONS

Using a fast temporary image overlay is key to faster build times. An overlay created on a *tmpfs* would be ideal, and can speed up I/O by an order of magnitude, compared to a slow HDD. If */tmp* or *$TMPDIR* are mountpoints for a tmpfs, then all should be fine by default.

However, tmpfs filesystems are backed by memory and swap on the host, so a build needing substantial disk space in the VM may fail. If this happens, the --overlay-dir option should be used to point to a host directory with more available disk space. Note that the base image itself must have been created with a suitable size, see the **--size** option to [sbuild-qemu-create(1)](/sbuild-qemu-create/1.md).

## LIMITATIONS

Due to the nature of sbuild's **--chroot-mode=autopkgtest**, not all sbuild options are supported yet. In particular, getting an interactive shell, for example using **--build-failed-command** is **NOT** possible. However, there are other ways to access the build environment (see below).

## VM ACCESS

sbuild's **--chroot-mode=autopkgtest** uses autopkgtest-virt-qemu under the hood, so you will find an SSH shell on port 10022 (or the first free port after that) if, and only if, the openssh-server package is installed in the VM.

As a further consequence of this chroot mode, what is stated in [autopkgtest-virt-qemu(1)](/autopkgtest-virt-qemu/1.md) generally also holds here.

## EXAMPLES

**$ sbuild-qemu -d unstable -s --arch-all FOO.dsc**

This will build the package **FOO.dsc** using **unstable** as the Distribution in the generated .changes file.

Because the **--image** option was not specified, an image with the name **unstable-autopkgtest-amd64.img** will be looked for first in the current directory, and then in **$IMAGEDIR***.*

*The* **-s** and **--arch-all** aren't known to sbuild-qemu, and are therefore will be passed on through to sbuild for it to use.

## ENVIRONMENT

**$IMAGEDIR** defaults to *~/.cache/sbuild*.

## COPYRIGHT

Copyright © 2020-2022 Christian Kastner \<ckk@debian.org\>

## SEE ALSO

[**sbuild**(1)](/sbuild/1.md), [**sbuild-qemu-create**(1)](/sbuild-qemu-create/1.md), [**sbuild-qemu-update**(1)](/sbuild-qemu-update/1.md).