Re: [PATCH v2 00/13] microvm: add acpi support

[Michael S. Tsirkin]

On Tue, May 05, 2020 at 03:42:52PM +0200, Gerd Hoffmann wrote:
> I know that not supporting ACPI in microvm is intentional.  If you still
> don't want ACPI this is perfectly fine, you can use the usual -no-acpi
> switch to toggle ACPI support.
> 
> These are the advantages you are going to loose then:
> 
>   (1) virtio-mmio device discovery without command line hacks (tweaking
>       the command line is a problem when not using direct kernel boot).
>   (2) Better IO-APIC support, we can use IRQ lines 16-23.
>   (3) ACPI power button (aka powerdown request) works.
>   (4) machine poweroff (aka S5 state) works.

Questions

- what's the tradeoff in startup time?
- what should be the default?

Based on above I'd be inclined to say default should stay no acpi and
users should enable acpi with an option.

> Together with seabios patches for virtio-mmio support this allows to
> boot standard fedora images (cloud, coreos, workstation live) with the
> microvm machine type.
> 
> git branch for testing (including updated seabios):
>       https://git.kraxel.org/cgit/qemu/log/?h=sirius/microvm
> 
> changes in v2:
>   * some acpi cleanups are an separate patch series now.
>   * switched to hw reduced acpi & generic event device.
>   * misc fixes here and there.
> 
> cheers,
>   Gerd
> 
> Gerd Hoffmann (13):
>   acpi: make build_madt() more generic.
>   acpi: create acpi-common.c and move madt code
>   acpi: madt: skip pci override on pci-less systems (microvm)
>   acpi: move acpi_build_facs to acpi-common.c
>   acpi: move acpi_init_common_fadt_data to acpi-common.c
>   acpi: move acpi_align_size to acpi-common.h
>   acpi: fadt: add hw-reduced sleep register support
>   acpi: generic event device for x86
>   microvm: add minimal acpi support
>   microvm: disable virtio-mmio cmdline hack
>   microvm: add acpi_dsdt_add_virtio() for x86
>   microvm: make virtio irq base runtime configurable
>   microvm/acpi: use GSI 16-23 for virtio
> 
>  hw/i386/acpi-common.h                  |  38 ++++
>  hw/i386/acpi-microvm.h                 |   6 +
>  include/hw/acpi/acpi-defs.h            |   2 +
>  include/hw/acpi/generic_event_device.h |  10 +
>  include/hw/i386/microvm.h              |  10 +-
>  hw/acpi/aml-build.c                    |   4 +-
>  hw/i386/acpi-build.c                   | 198 +-------------------
>  hw/i386/acpi-common.c                  | 206 ++++++++++++++++++++
>  hw/i386/acpi-microvm.c                 | 249 +++++++++++++++++++++++++
>  hw/i386/generic_event_device_x86.c     | 114 +++++++++++
>  hw/i386/microvm.c                      |  36 +++-
>  hw/i386/Kconfig                        |   1 +
>  hw/i386/Makefile.objs                  |   3 +
>  13 files changed, 676 insertions(+), 201 deletions(-)
>  create mode 100644 hw/i386/acpi-common.h
>  create mode 100644 hw/i386/acpi-microvm.h
>  create mode 100644 hw/i386/acpi-common.c
>  create mode 100644 hw/i386/acpi-microvm.c
>  create mode 100644 hw/i386/generic_event_device_x86.c
> 
> -- 
> 2.18.4