Re: [Qemu-devel] [PATCH for-3.0] pc: Use "3.0+" constant as default SMBIOS version

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

On Mon, Jul 09, 2018 at 05:37:31PM -0300, Eduardo Habkost wrote:
> Every time we create new PC machine-types in QEMU, the defaults
> for SMBIOS fields change unnecessarily because the version field
> defaults to MachineClass::name.
> 
> This can cause unexpected side-effects, like triggering license
> reactivation on guest software, or changing the VM memory layout
> because of BIOS table size changes.
> 
> Change the SMBIOS version string for pc-*-3.0 to "3.0+" to avoid
> doing this on every QEMU release, and keep compatible version
> strings on older machine-types using a new
> MachineClass::smbios_version field.
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
> I just noticed that we started using mc->name on arm/virt since
> commit dfadc3bfb458efefb72e13a57b62f138c464a577.
> Should arm/virt start using "3.0+" too?
> ---
>  include/hw/i386/pc.h | 3 +++
>  hw/i386/pc.c         | 1 +
>  hw/i386/pc_piix.c    | 5 +++--
>  hw/i386/pc_q35.c     | 3 ++-
>  4 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 4d99d69681..aea0fcaadb 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -134,6 +134,9 @@ struct PCMachineClass {
>  
>      /* use DMA capable linuxboot option rom */
>      bool linuxboot_dma_enabled;
> +
> +    /* Version field for SMBIOS Type 1, Type 2, Type 3, and Type 4 structs */
> +    const char *smbios_version;
>  };
>  
>  #define TYPE_PC_MACHINE "generic-pc-machine"
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 50d5553991..47877e7071 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -2379,6 +2379,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
>      pcmc->acpi_data_size = 0x20000 + 0x8000;
>      pcmc->save_tsc_khz = true;
>      pcmc->linuxboot_dma_enabled = true;
> +    pcmc->smbios_version = "3.0+";
>      assert(!mc->get_hotplug_handler);
>      mc->get_hotplug_handler = pc_get_hotpug_handler;
>      mc->cpu_index_to_instance_props = pc_cpu_index_to_props;

I suspect 3.00 is cleaner for tools that happen to
parse the version as a numeral as it always was in the past,
even if it's not exact.

> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index dc09466b3e..f19c8b82d0 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -168,10 +168,9 @@ static void pc_init1(MachineState *machine,
>      pc_guest_info_init(pcms);
>  
>      if (pcmc->smbios_defaults) {
> -        MachineClass *mc = MACHINE_GET_CLASS(machine);
>          /* These values are guest ABI, do not change */
>          smbios_set_defaults("QEMU", "Standard PC (i440FX + PIIX, 1996)",
> -                            mc->name, pcmc->smbios_legacy_mode,
> +                            pcmc->smbios_version, pcmc->smbios_legacy_mode,
>                              pcmc->smbios_uuid_encoded,
>                              SMBIOS_ENTRY_POINT_21);
>      }
> @@ -440,9 +439,11 @@ DEFINE_I440FX_MACHINE(v3_0, "pc-i440fx-3.0", NULL,
>  
>  static void pc_i440fx_2_12_machine_options(MachineClass *m)
>  {
> +    PCMachineClass *pcmc = PC_MACHINE_CLASS(m);
>      pc_i440fx_3_0_machine_options(m);
>      m->is_default = 0;
>      m->alias = NULL;
> +    pcmc->smbios_version = m->name;
>      SET_MACHINE_COMPAT(m, PC_COMPAT_2_12);
>  }
>  
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 532241e3f8..d6551ed8e9 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -146,7 +146,7 @@ static void pc_q35_init(MachineState *machine)
>      if (pcmc->smbios_defaults) {
>          /* These values are guest ABI, do not change */
>          smbios_set_defaults("QEMU", "Standard PC (Q35 + ICH9, 2009)",
> -                            mc->name, pcmc->smbios_legacy_mode,
> +                            pcmc->smbios_version, pcmc->smbios_legacy_mode,
>                              pcmc->smbios_uuid_encoded,
>                              SMBIOS_ENTRY_POINT_21);
>      }
> @@ -336,6 +336,7 @@ static void pc_q35_2_11_machine_options(MachineClass *m)
>  
>      pc_q35_2_12_machine_options(m);
>      pcmc->default_nic_model = "e1000";
> +    pcmc->smbios_version = m->name;
>      SET_MACHINE_COMPAT(m, PC_COMPAT_2_11);
>  }
>  
> -- 
> 2.18.0.rc1.1.g3f1ff2140