Re: [PATCH 00/13] microvm: add acpi support

[Gerd Hoffmann]

  Hi,

> The main reason for not having ACPI was the time that it took to start;

Yep, ACPI needs additional boot time.  Shouldn't be a big difference
though, microvm acpi only declares some devices and has small tables.
Also no acpi methods, so no interpreter work.  Maybe it is mostly the
additional time needed to log the ACPI stuff to the serial console
(didn't try yet to time boots with "quiet").

On the other hand you have effects like this:
Without acpi the kernel checks whenever hardware is present:

    # dmesg | grep i8042
    [    0.334403] i8042: PNP: No PS/2 controller found.
    [    0.334619] i8042: Probing ports directly.
    [    1.370573] i8042: No controller found

With acpi the kernel trusts the firmware and doesn't bother
probing directly:

    # dmesg | grep i8042
    [    0.345500] i8042: PNP: No PS/2 controller found.

cheers,
  Gerd