linux-yocto/tools/testing/selftests/arm64/fp

This directory contains a mix of tests integrated with kselftest and standalone stress tests.

kselftest tests

sve-probe-vls - Checks the SVE vector length enumeration interface sve-ptrace - Checks the SVE ptrace interface

Running the non-kselftest tests

sve-stress performs an SVE context switch stress test, as described below.

(The fpsimd-stress test works the same way; just substitute "fpsimd" for "sve" in the following commands.)

The test runs until killed by the user.

If no context switch error was detected, you will see output such as the following:

$ ./sve-stress (wait for some time) ^C Vector length: 512 bits PID: 1573 Terminated by signal 15, no error, iterations=9467, signals=1014 Vector length: 512 bits PID: 1575 Terminated by signal 15, no error, iterations=9448, signals=1028 Vector length: 512 bits PID: 1577 Terminated by signal 15, no error, iterations=9436, signals=1039 Vector length: 512 bits PID: 1579 Terminated by signal 15, no error, iterations=9421, signals=1039 Vector length: 512 bits PID: 1581 Terminated by signal 15, no error, iterations=9403, signals=1039 Vector length: 512 bits PID: 1583 Terminated by signal 15, no error, iterations=9385, signals=1036 Vector length: 512 bits PID: 1585 Terminated by signal 15, no error, iterations=9376, signals=1039 Vector length: 512 bits PID: 1587 Terminated by signal 15, no error, iterations=9361, signals=1039 Vector length: 512 bits PID: 1589 Terminated by signal 15, no error, iterations=9350, signals=1039

If an error was detected, details of the mismatch will be printed instead of "no error".

Ideally, the test should be allowed to run for many minutes or hours to maximise test coverage.

KVM stress testing

To try to reproduce the bugs that we have been observing, sve-stress should be run in parallel in two KVM guests, while simultaneously running on the host.

1. Start 2 guests, using the following command for each:

$ lkvm run --console=virtio -pconsole=hvc0 --sve Image

(Depending on the hardware GIC implementation, you may also need --irqchip=gicv3. New kvmtool defaults to that if appropriate, but I can't remember whether my branch is new enough for that. Try without the option first.)

Kvmtool occupies the terminal until you kill it (Ctrl+A x), or until the guest terminates. It is therefore recommended to run each instance in separate terminal (use screen or ssh etc.) This allows multiple guests to be run in parallel while running other commands on the host.

Within the guest, the host filesystem is accessible, mounted on /host.

2. Run the sve-stress on each guest with the Vector-Length set to 32: guest$ ./vlset --inherit 32 ./sve-stress

3. Run the sve-stress on the host with the maximum Vector-Length: host$ ./vlset --inherit --max ./sve-stress

Again, the test should be allowed to run for many minutes or hours to maximise test coverage.

If no error is detected, you will see output from each sve-stress instance similar to that illustrated above; otherwise details of the observed mismatches will be printed.