The Design and Implementation of the Anykernel and Rump Kernels

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• Rapid prototyping: One of the reasons for implementing the 4.4BSD logstructured
file system cleaner in userspace was the ability to easily try different
cleaning algorithms [100]. Using rump kernels these trials can easily be
done without having to split the runtime environment and pay the overhead
for easy development during production use.
Since it is difficult to measure the convenience of kernel development by any formal
metric, we would like to draw the following analogy: kernel development on real
hardware is to using emulators as using emulators is to developing with rump kernels.
4.5.2 Test Suites
A test suite consists of test cases. A test case produces a result to the question “is
this feature working properly?”, while the test suite produces a result to the question
“are all the features working properly?”. Ideally, the test suite involves for example
checking no bug ever encountered has resurfaced [57].
The NetBSD testing utility is called the Automated Testing Framework (ATF )[75].
The qualifier “automated” refers to the fact that the test suite end user can run the
test suite with a single command and expect to get a test report of all the test cases.
The framework takes care of all the rest. ATF consists of tools for running tests
and generating reports. One goal of ATF is to make tests easy to run, so that they
are actually run by developers and users.
Automated batchmode testing exposes several problems in the straightforward approach
of using the test suite host kernel as the test target:
1. A failed test can cause a kernel panic and cause the entire test suite run to
fail.