You didn't answer any of the questions proposed by the outlined scenario.
Until you answer how you've solved the "I want to make sure my data is written to disk before the hypervisor powers off the virtual machine at the end of the successful run" problem, then I claim that this is absolutely not voodoo.
I suggest you actually read the documentation of all of these things before you start claiming that `fsync()` is exclusively the purpose of kernel, driver, or bootloader developers.
Until you answer how you've solved the "I want to make sure my data is written to disk before the hypervisor powers off the virtual machine at the end of the successful run" problem, then I claim that this is absolutely not voodoo.
I suggest you actually read the documentation of all of these things before you start claiming that `fsync()` is exclusively the purpose of kernel, driver, or bootloader developers.