Rapido helps you quickly test Linux kernel changes.
git clone https://github.com/rapido-linux/rapido.git && cd rapido
cargo build --offline --release
./rapido cut simple-example # boot a throwaway VM using the host kernelClone this repository and install the following dependencies:
- QEMU: Boots a given VM image and compiled Linux kernel on the local system
- systemd-networkd: Configures networking within Rapido VMs (optional)
- iproute2: Configures Bridge and TAP devices on the host (optional)
Rapido obtains all dependencies from the local system; no magic images
or internet downloads are necessary. Individual cut scripts may require extra
local dependencies. E.g. cut/fstests_btrfs.sh runs xfstests, which is obtained
from the configured FSTESTS_SRC path.
Rapido is primarily configured via rapido.conf. To boot a custom Linux
kernel, copy rapido.conf.example and set the
KERNEL_SRC parameter to the path of your compiled kernel source.
Test VM images may be "cut" with or without network support. For
networking, per-VM systemd-networkd configuration should be specified in
the net-conf directory. An example is provided in
net-conf.example.
The rapido setup-network command should be run as root to configure a
bridge network device and VM-assigned tap devices.
By default, the bridge network is isolated, and isn't connected to any
physical adapters.
Depending on which kernel component or functionality you'd like to test,
choose a cut script to generate a VM image. E.g.
./rapido cut fstests-btrfsThe cut script collects all required kernel modules and user-space dependencies
from the local system and writes a VM initramfs image to initrds/myinitrd.
Rapido attempts to use the copy_file_range() syscall when copying file data
to 4K-aligned initramfs destination offsets. This allows the host filesystem
to avoid file data duplication by using reflinks where supported, e.g. on XFS
and Btrfs.
Once generated, a VM using the image and kernel will boot immediately. Subsequent VMs can be booted manually via:
./rapido bootRapido can be used to test kernels on confined systems such as GitHub CI
Runners. See Rapido's own .github/workflows/ci.yml
file as an example for compiling and booting a mainline kernel VM from a
ubuntu-latest GitHub Runner.
Rapido can be easily extended to test most kernel functionality. Simply copy the cut/simple_example.sh and autorun/simple_example.sh scripts and modify them to suit your needs. The example scripts are fully annotated.
Please raise any questions or issues upstream via https://github.com/rapido-linux/rapido/issues.
Also see troubleshooting tips.
ASCII art
+------------------------+
| |
| Rapido 'cut' script |
| |
| +--------------------+ | +-----+
| | | | | |
| | File manifest: | | | |
+------------------------+ | | • Kernel modules | | | |
| | | | • User space files | | | |
| Userspace dependencies | | | | | | |
| E.g. | | +---------+----------+ | | |
| • xfstests, blktests | | | <----+ |
| • Ceph conf + binaries | | +---------v----------+ | | |
| • Samba | | | | | | |
| • etc. +--->--+----> "rapido-cut.rs" | | | r |
| | | | | initramfs creator | | | a |
+------------------------+ ^ | | | | | p |
| | +---------+----------+ | | i |
+-------------------------+ | | | | | d |
| | | +------------------------+ | o |
| Rapido 'autorun' files +-->--+ | | . |
| | | +---------v----------+ | c |
+-------------------------+ | | | | o |
| | Initramfs | | n |
^ | • Includes all | | f |
+------------------------+ | | kernel and user | | |
| Compiled Linux Kernel | | | dependencies | | / |
| | | | | | |
| +---------+ | | +---------+----------+ | n |
| | Modules +---------------->--+ | | e |
| +---------+ | +------------------------+ | t |
| | | | | | |
| +---------+ | | "rapido-vm.rs" | | c |
| | bzImage +---------------->--+ | | | | o |
| +---------+ | | | +--------v----+ | | n |
| | | | | | <----+ f |
+------------------------+ +-----> QEMU / KVM | | | |
| | | | | |
| +--------+----+ | | |
| | | +--+--+
+------------------------+ |
=================== | |
| Virtual network O--------+ +-----------v---------------+ v
=========^========= | ++ | |
| | !| Virtual Machine | |
| | !| • Console redirected via | |
| +---oO stdin and stdout <----+
+-----------+------------+ !| • "rapido-init.rs" and | |
| | !| 'autorun' executed | |
| Rapido "setup-network" | !| | v
| | !+--------------------------++ |
+-----------^------------+ +~~~~~~~~~~~~~~~~~~~~~~~~~~~+ |
| |
+------------------------------<------------------------+