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841a3dae88
As noted by commit 738261290f ("CI: temporarily disable vmtest"),
vmtest was generating too much traffic to the Dropbox shared folder that
hosted vmtest kernels. Instead, we can store kernel packages as GitHub
release assets. Update the code for downloading and uploading vmtest
assets, and also add a scheduled GitHub action to build new kernels
every Monday so I don't have to remember to do it manually.
This also drops vmtest support for 5.6-5.9, which now fail to build with
newer binutils due to the issue fixed in Linux kernel commit
1d489151e9f9 ("objtool: Don't fail on missing symbol table").
Signed-off-by: Omar Sandoval <osandov@osandov.com>
48 lines
2.3 KiB
ReStructuredText
48 lines
2.3 KiB
ReStructuredText
drgn VM Testing
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===============
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drgn has a significant amount of code (both core and in helpers) which is
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dependent on the Linux kernel version. This code is tested on multiple Linux
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kernel versions in a virtual machine. These tests can be run on all supported
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kernels with ``python3 setup.py test -K``. This requires QEMU, BusyBox, and
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zstd to be installed.
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Tests can also be run on specific kernels with ``-k``. This takes a
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comma-separated list of kernels which are wildcard patterns (e.g., ``5.6.*``)
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matching a kernel release hosted on GitHub (see below).
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Architecture
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------------
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The goal of vmtest is to run tests in the same userspace environment as the
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host, but with a different kernel. The host runs the virtual machine with `QEMU
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<https://www.qemu.org/>`_ (see the `vmtest.vm <vm.py>`_ module).
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The guest mounts the host's root filesystem as its own root filesystem via
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`VirtFS <https://www.linux-kvm.org/page/VirtFS>`_. It is mounted read-only for
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safety. To support modifications, the guest uses `OverlayFS
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<https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt>`_ to
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overlay a read-write tmpfs over the VirtFS root. It also mounts the kernel
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modules and vmlinux via VirtFS.
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The guest runs a `BusyBox <https://www.busybox.net/>`_ shell script as init
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which sets up the system and filesystem hierarchy, runs a command, and returns
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the exit status via `virtio-serial
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<https://fedoraproject.org/wiki/Features/VirtioSerial>`_.
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This infrastructure is all generic. The drgn-specific parts are:
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1. The kernel builds. These are configured with a minimal configuration
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including everything required to run drgn and the Linux kernel helper tests.
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Each build is packaged as a tarball containing ``vmlinux``, ``vmlinuz``, and
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kernel modules. These packages are hosted in a `GitHub release
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<https://github.com/osandov/drgn/releases/tag/vmtest-assets>`_. They are
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managed via the GitHub API by the `vmtest.manage <manage.py>`_ CLI and
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downloaded by the `vmtest.download <download.py>`_ module.
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2. The test command itself. This is just some ``setup.py`` glue and the proper
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invocation of the Python `unittest command line interface
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<https://docs.python.org/3/library/unittest.html#test-discovery>`_.
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The ``vmtest.vm`` and ``vmtest.download`` modules also have CLIs for testing
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purposes. These are subject to change.
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