projects / thirdparty / systemd.git / blame
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|---|---|---|
| 34c6b7d9 LP |
1 | --- |
| 2 | title: VM Interface | |
| 3 | category: Interfaces | |
| 4 | layout: default | |
| 5 | SPDX-License-Identifier: LGPL-2.1-or-later | |
| 6 | --- | |
| 7 | ||
| 8 | # The VM Interface | |
| 9 | ||
| 10 | Also consult [Writing Virtual Machine or Container | |
| 11 | Managers](https://systemd.io/WRITING_VM_AND_CONTAINER_MANAGERS). | |
| 12 | ||
| 13 | systemd has a number of interfaces for interacting with virtual machine | |
| 14 | managers, when systemd is used inside of a VM. If you work on a VM manager, | |
| 15 | please consider supporting the following interfaces. | |
| 16 | ||
| 17 | 1. systemd supports passing immutable binary data blobs with limited size and | |
| 18 | restricted access to services via the `ImportCredential=`, `LoadCredential=` | |
| 19 | and `SetCredential=` settings. These credentials may be passed into a system | |
| 20 | via SMBIOS Type 11 vendor strings, see | |
| 21 | [systemd(1)](https://www.freedesktop.org/software/systemd/man/latest/systemd.html) | |
| 6e0abf5f | 22 | for details. This concept may be used to flexibly configure various facets |
| 34c6b7d9 LP |
23 | ot the guest system. See |
| 24 | [systemd.system-credentials(7)](https://www.freedesktop.org/software/systemd/man/latest/systemd.system-credentials.html) | |
| 25 | for a list of system credentials implemented by various systemd components. | |
| 26 | ||
| 27 | 2. Readiness, information about various system properties and functionality, as | |
| 28 | well as progress of boot may be reported by systemd to a machine manager via | |
| 29 | the `sd_notify()` protocol via `AF_VSOCK` sockets. The address of this | |
| 30 | socket may be configured via the `vmm.notify_socket` system credential. See | |
| 31 | [systemd(1)](https://www.freedesktop.org/software/systemd/man/latest/systemd.html). | |
| 32 | ||
| 33 | 3. The | |
| 34 | [systemd-ssh-generator(8)](https://www.freedesktop.org/software/systemd/man/latest/systemd-ssh-generator.html) | |
| 35 | functionality will automatically bind SSH login functionality to `AF_VSOCK` | |
| 36 | port 22, if the system runs in a VM. | |
| 37 | ||
| 38 | 4. If not initialized yet the system's | |
| 39 | [machine-id(5)](https://www.freedesktop.org/software/systemd/man/latest/machine-id.html) | |
| 40 | is automatically set to the SMBIOS product UUID if available and invocation | |
| 41 | in an VM environment is detected. | |
| 42 | ||
| 43 | 5. The | |
| 44 | [`systemd-boot(7)`](https://www.freedesktop.org/software/systemd/man/latest/systemd-boot.html) | |
| 45 | and | |
| 46 | [`systemd-stub(7)`](https://www.freedesktop.org/software/systemd/man/latest/systemd-stub.html) | |
| 47 | components support two SMBIOS Type 11 vendor strings that may be used to | |
| 48 | extend the kernel command line of booted Linux environments: | |
| 49 | `io.systemd.stub.kernel-cmdline-extra=` and | |
| 50 | `io.systemd.boot.kernel-cmdline-extra=`. | |
| 51 | ||
| 52 | Also see | |
| 53 | [smbios-type-11(7)](https://www.freedesktop.org/software/systemd/man/latest/smbios-type-11.html) | |
| 54 | for a list of supported SMBIOS Type 11 vendor strings. |