Re: [Qemu-devel] [PATCH 2/4] q35: set split kernel irqchip as default

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Dec 19, 2018 at 04:50:36PM +0800, Peter Xu wrote:
> Starting from QEMU 4.0, let's specify "split" as the default value for
> kernel-irqchip.
> 
> So for QEMU>=4.0 we'll have: allowed=Y,required=N,split=Y
>    for QEMU<=3.1 we'll have: allowed=Y,required=N,split=N
>    (omitting all the "kernel_irqchip_" prefix)
> 
> Note that this "split" is optional - we'll first try to enable split
> kernel irqchip, and we'll fall back to complete kernel irqchip if we
> found that the kernel capability is missing.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>

I'm split on this one ;)
On the one hand why not make pc and q35 are consistent here?
On the other hand we really should work to leave PC alone
as much as we can ...

Paolo, what's your opinion?


> ---
>  hw/core/machine.c   | 2 ++
>  hw/i386/pc_q35.c    | 2 ++
>  include/hw/boards.h | 1 +
>  3 files changed, 5 insertions(+)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index c51423b647..4439ea663f 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -653,8 +653,10 @@ static void machine_class_base_init(ObjectClass *oc, void *data)
>  static void machine_initfn(Object *obj)
>  {
>      MachineState *ms = MACHINE(obj);
> +    MachineClass *mc = MACHINE_GET_CLASS(obj);
>  
>      ms->kernel_irqchip_allowed = true;
> +    ms->kernel_irqchip_split = mc->default_kernel_irqchip_split;
>      ms->kvm_shadow_mem = -1;
>      ms->dump_guest_core = true;
>      ms->mem_merge = true;
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 58459bdab5..d2fb0fa49f 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -304,6 +304,7 @@ static void pc_q35_machine_options(MachineClass *m)
>      m->units_per_default_bus = 1;
>      m->default_machine_opts = "firmware=bios-256k.bin";
>      m->default_display = "std";
> +    m->default_kernel_irqchip_split = true;
>      m->no_floppy = 1;
>      machine_class_allow_dynamic_sysbus_dev(m, TYPE_AMD_IOMMU_DEVICE);
>      machine_class_allow_dynamic_sysbus_dev(m, TYPE_INTEL_IOMMU_DEVICE);
> @@ -323,6 +324,7 @@ DEFINE_Q35_MACHINE(v4_0, "pc-q35-4.0", NULL,
>  static void pc_q35_3_1_machine_options(MachineClass *m)
>  {
>      pc_q35_4_0_machine_options(m);
> +    m->default_kernel_irqchip_split = false;
>      m->alias = NULL;
>      SET_MACHINE_COMPAT(m, PC_COMPAT_3_1);
>  }
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index f82f28468b..362384815e 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -195,6 +195,7 @@ struct MachineClass {
>      const char *hw_version;
>      ram_addr_t default_ram_size;
>      const char *default_cpu_type;
> +    bool default_kernel_irqchip_split;
>      bool option_rom_has_mr;
>      bool rom_file_has_mr;
>      int minimum_page_bits;
> -- 
> 2.17.1