Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite

[Claudio Fontana]

Hi,

On 17.06.2016 10:14, Chao Peng wrote:
> This patchset is against commit 585fcd4 (Merge remote-tracking branch
> 'remotes/bonzini/tags/for-upstream' into staging) on master branch. I
> also put it on github:
> 
> https://github.com/chao-p/qemu pc-lite-v1
>  
> Although we have run the patchset internally for a while but it is still
> considered as RFC. Any comments (coding style or design issue) are
> welcome.
> 
> Introduction
> ============
> The patch series introduces a new platform pc-lite, which is designed to
> be a virtual and light weight x86 PC platform. It is not designed to be
> compatible with old hardware and system. Instead, It removes the burden
> of legacy devices and emulates new fast hardware as much as possible. It
> is expected to be used together with optimized guest (though unoptimized
> guest works as well) to gain fast booting and small footprint benefits
> that are difficult to achieve for traditional hardware-emulated
> platform.
> 
> Basically:
> - it removes old ISA devices and support only PCI devices;
> - it removes 8259, instead use MSI as much as possible. IOAPIC and PCI
>   PIN are still kept to support ACPI SCI;
> - it supports PCIE ( you can use MMFG instead of 0xcf8/0xcfc port
>   access);
> - it gets rid of legacy firmware interfaces and supports ACPI tables;
> - it loads guest kernel directly, no BIOS, no bootloader, no realmode
>   code;
> - it supports CPU/memory/PCI hotplug;
> - it is FAST;
> 
> However:
> - it supports KVM-host only at present;
> - it supports Linux-guest only at present;
> - You may need carefully configure guest kernel;
> - You are forced to use virtio-serial-pci, old 8250/16550 is not there;
> 
> Want to have a try?
> ===================

The combination of devices removed/supported seems a bit arbitrary to me.
The use in this text of "legacy" and non-"legacy" is also arbitrary if not 
given a definition.

What is the use case of this new platform?

Care to share your numbers about how FAST is FAST? Like how much time you need 
to boot from qemu launch to the guest being booted, and on which hardware, and 
which guest kernel configuration?

Ciao,

Claudio

> 
> Please follow https://github.com/chao-p/qemu-lite-tools.
> 
> Thanks,
> Chao
> 
> Chao Peng (6):
>   acpi: introduce light weight ACPI PM emulation pm-lite
>   pci: introduce light weight PCIE Host emulation pci-lite
>   acpi: add support for pc-lite platform
>   pc: skip setting CMOS data when RTC device is unavailable
>   pc: support direct loading protected/long mode kernel
>   pc: introduce light weight PC board pc-lite
> 
> Haozhong Zhang (3):
>   acpi: expose data structurs and functions of BIOS linker loader
>   acpi: expose acpi_checksum()
>   acpi: patch guest ACPI for pc-lite
> 
>  default-configs/i386-softmmu.mak     |   1 +
>  default-configs/x86_64-softmmu.mak   |   1 +
>  docs/specs/acpi_cpu_hotplug.txt      |   1 +
>  hw/acpi/Makefile.objs                |   2 +-
>  hw/acpi/bios-linker-loader.c         |  83 +------
>  hw/acpi/core.c                       |   2 +-
>  hw/acpi/nvdimm.c                     |   6 +-
>  hw/acpi/pm_lite.c                    | 446 
> +++++++++++++++++++++++++++++++++++
>  hw/i386/Makefile.objs                |   2 +-
>  hw/i386/acpi-build.c                 | 180 +++++++++-----
>  hw/i386/pc.c                         | 263 ++++++++++++++++++---
>  hw/i386/pc_lite.c                    | 205 ++++++++++++++++
>  hw/i386/pc_lite_acpi.c               | 299 +++++++++++++++++++++++
>  hw/i386/pc_piix.c                    |   2 +
>  hw/i386/pc_q35.c                     |   2 +
>  hw/pci-host/Makefile.objs            |   1 +
>  hw/pci-host/pci_lite.c               | 259 ++++++++++++++++++++
>  include/hw/acpi/acpi.h               |   2 +
>  include/hw/acpi/bios-linker-loader.h |  85 +++++++
>  include/hw/acpi/pc-hotplug.h         |   1 +
>  include/hw/acpi/pm_lite.h            |   6 +
>  include/hw/i386/pc.h                 |  17 ++
>  include/hw/i386/pc_lite_acpi.h       |  10 +
>  23 files changed, 1697 insertions(+), 179 deletions(-)
>  create mode 100644 hw/acpi/pm_lite.c
>  create mode 100644 hw/i386/pc_lite.c
>  create mode 100644 hw/i386/pc_lite_acpi.c
>  create mode 100644 hw/pci-host/pci_lite.c
>  create mode 100644 include/hw/acpi/pm_lite.h
>  create mode 100644 include/hw/i386/pc_lite_acpi.h
>