Re: [Qemu-arm] [PATCH 1/1] mach-virt: Change default cpu and gic-version setting to "max"

[Peter Maydell]

On 9 April 2018 at 16:49, Wei Huang <address@hidden> wrote:
> Running mach-virt machine types (i.e. "-M virt") on different systems can
> result in various misleading warnings if -cpu and/or gic-version not 
> specified.
> For KVM, this can be solved mostly by using "host" type. But the "host" type
> doesn't work for TCG. Compared with "host", the "max" type not only supports
> auto detection under KVM mode, but also works with TCG.
> So this patch set "max" as the default types for both -cpu and gic-version.

Using "max" will make the VM not migratable by default, and also
means that the behaviour might differ between host machines and
between different QEMU versions. I'm not sure we want that for the
default ?

> Signed-off-by: Wei Huang <address@hidden>
> ---
>  hw/arm/virt.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 94dcb125d3..1a9d68b8d5 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -1555,7 +1555,7 @@ static void virt_machine_class_init(ObjectClass *oc, 
> void *data)
>      mc->minimum_page_bits = 12;
>      mc->possible_cpu_arch_ids = virt_possible_cpu_arch_ids;
>      mc->cpu_index_to_instance_props = virt_cpu_index_to_props;
> -    mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a15");
> +    mc->default_cpu_type = ARM_CPU_TYPE_NAME("max");
>      mc->get_default_cpu_node_id = virt_get_default_cpu_node_id;
>  }
>
> @@ -1609,13 +1609,13 @@ static void virt_2_12_instance_init(Object *obj)
>                                      "Set on/off to enable/disable using "
>                                      "physical address space above 32 bits",
>                                      NULL);
> -    /* Default GIC type is v2 */
> -    vms->gic_version = 2;
> +    /* Default GIC type is max */
> +    vms->gic_version = -1;
>      object_property_add_str(obj, "gic-version", virt_get_gic_version,
>                          virt_set_gic_version, NULL);
>      object_property_set_description(obj, "gic-version",
> -                                    "Set GIC version. "
> -                                    "Valid values are 2, 3 and host", NULL);
> +                                    "Set GIC version. Valid values are 2, 3, 
> "
> +                                    "host, and max", NULL);

This change in the help string is a bug fix not related to the
rest of the patch. You should send that as a separate patch,
because we want that regardless of what we do about the default
value.

thanks
-- PMM