Re: [Qemu-devel] [PATCH] pc: piix4_pm: init legacy PCI hotplug when running on Xen

[Zhang, Yang Z]

Igor Mammedov wrote on 2014-05-23:
> if user starts QEMU with "-machine pc,accel=xen", then compat property
> in xenfv won't work and it would cause error:
> "Unsupported bus. Bus doesn't have property 'acpi-pcihp-bsel' set"
> when PCI device is added with -device on QEMU CLI.
> 
> In case of Xen instead of using compat property, just use the fact
> that xen doesn't use QEMU's fw_cfg/acpi tables to switch piix4_pm into
> legacy PCI hotplug mode when Xen is enabled.

I am wondering why Xen cannot use new mechanism to do the hotplug.

> 
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
>  hw/acpi/piix4.c   |  3 +++
>  hw/i386/pc_piix.c | 11 -----------
>  2 files changed, 3 insertions(+), 11 deletions(-)
> diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c index 227ea30..12542c3
> 100644 --- a/hw/acpi/piix4.c +++ b/hw/acpi/piix4.c @@ -501,6 +501,9 @@
> I2CBus *piix4_pm_init(PCIBus *bus, int devfn, uint32_t smb_io_base,
>      s->irq = sci_irq;
>      s->smi_irq = smi_irq;
>      s->kvm_enabled = kvm_enabled;
> +    if (!fw_cfg) {
> +        s->use_acpi_pci_hotplug = false;
> +    }
> 
>      qdev_init_nofail(dev);
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c index
> a13e8d6..067ff0c 100644 --- a/hw/i386/pc_piix.c +++ b/hw/i386/pc_piix.c
> @@ -840,17 +840,6 @@ static QEMUMachine xenfv_machine = {
>      .max_cpus = HVM_MAX_VCPUS,
>      .default_machine_opts = "accel=xen",
>      .hot_add_cpu = pc_hot_add_cpu,
> -    .compat_props = (GlobalProperty[]) {
> -        /* xenfv has no fwcfg and so does not load acpi from QEMU.
> -         * as such new acpi features don't work.
> -         */
> -        {
> -            .driver   = "PIIX4_PM",
> -            .property = "acpi-pci-hotplug-with-bridge-support",
> -            .value    = "off",
> -        },
> -        { /* end of list */ }
> -    },
>  };
>  #endif


Best regards,
Yang