9b1d27b2fa
Include the complete list of threads of all running processes in the FreeBSDKernel plugin. This makes it possible to inspect the states (including partial register dumps from PCB) of all kernel and userspace threads at the time of crash, or at the time of reading /dev/mem first. Differential Revision: https://reviews.llvm.org/D116255
46 lines
1.7 KiB
ReStructuredText
46 lines
1.7 KiB
ReStructuredText
How to create vmcores for tests
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===============================
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1. Boot a FreeBSD VM with as little memory as possible and create a core dump
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per `FreeBSD Handbook Kernel Debugging Chapter`_. Note that you may need to
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reboot with more memory after the kernel panic as otherwise savecore(8) may
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fail.
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For instance, I was able to boot FreeBSD and qemu-system-x86_64 with 128 MiB
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RAM but had to increase it to 256 MiB for the boot after kernel panic.
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2. Transfer the kernel image (``/boot/kernel/kernel``) and vmcore
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(``/var/crash/vmcore.latest``) from the VM.
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3. Patch libfbsdvmcore using ``libfbsdvmcore-hacks.patch`` and build LLDB
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against the patched library.
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4. Patch LLDB using ``lldb-minimize-processes.patch`` and build it.
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WARNING: LLDB will now modify core files in order to make the resulting
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test vmcores smaller. Make a backup if necessary.
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5. Do a test run of ``test.script`` in LLDB against the kernel + vmcore::
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lldb -b -s test.script --core /path/to/core /path/to/kernel
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If everything works fine, the LLDB output should be interspersed with
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``%RD`` lines. The vmcore will also be modified to shorten the process
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list in ``allproc``.
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6. Open the vmcore in the patched LLDB again and choose interesting threads
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for testing. Update thread numbers in ``test.script`` if necessary.
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7. Use the ``copy-sparse.py`` tool to create a sparse version of the vmcore::
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lldb -b -s test.script --core /path/to/core /path/to/kernel |
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grep '^% RD' | python copy-sparse.py /path/to/core vmcore.sparse
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8. Compress the sparse vmcore file using ``bzip2``::
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bzip2 -9 vmcore.sparse
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.. _FreeBSD Handbook Kernel Debugging Chapter:
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https://docs.freebsd.org/en/books/developers-handbook/kerneldebug/
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