Re: [Qemu-devel] [PATCH v2 1/2] pc: Move q35 compat props to PC_COMPAT_*

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

On Tue, Jun 24, 2014 at 11:04:44PM -0300, Eduardo Habkost wrote:
> For each compat property on PC_Q35_COMPAT_*, there are only two
> possibilities:
> 
>  * If the device is never instantiated when using a machine other than
>    pc-q35, then the compat property can be safely added to
>    PC_COMPAT_*;
>  * If the device can be instantiated when using a machine other than
>    pc-q35, that means the other machines also need the compat property
>    to be set.
> That means we don't need separate PC_Q35_COMPAT_* macros at all, today.
> 
> The hpet.hpet-intcap case is interesting: piix and q35 do have something
> that emulates different defaults, but the machine-specific default is
> applied _after_ compat_props are applied, by simply checking if the
> property is zero (which is the real default on the hpet code).
> 
> The hpet.hpet-intcap=0x4 compat property can (should?) be applied to
> piix too, because 0x4 was the default on both piix and q35 before the
> hpet-intcap property was introduced.

True. That's a very good explanation, thanks!

> Now, if one day we change the default HPET intcap on one of the PC
> machine-types again, we may want to introduce PC_{Q35,I440FX}_COMPAT
> macros. But while we don't need that, we can keep the code simple.
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> Cc: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
> Cc: Peter Maydell <peter.maydell@linaro.org>

Small patch, less code, same functionality, what's not to like.

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  hw/i386/pc_q35.c     | 10 +++++-----
>  include/hw/i386/pc.h | 55 +++++++++++++++++-----------------------------------
>  2 files changed, 23 insertions(+), 42 deletions(-)
> 
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 155db99..36b6ab0 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -361,7 +361,7 @@ static QEMUMachine pc_q35_machine_v2_0 = {
>      .name = "pc-q35-2.0",
>      .init = pc_q35_init_2_0,
>      .compat_props = (GlobalProperty[]) {
> -        PC_Q35_COMPAT_2_0,
> +        PC_COMPAT_2_0,
>          { /* end of list */ }
>      },
>  };
> @@ -373,7 +373,7 @@ static QEMUMachine pc_q35_machine_v1_7 = {
>      .name = "pc-q35-1.7",
>      .init = pc_q35_init_1_7,
>      .compat_props = (GlobalProperty[]) {
> -        PC_Q35_COMPAT_1_7,
> +        PC_COMPAT_1_7,
>          { /* end of list */ }
>      },
>  };
> @@ -385,7 +385,7 @@ static QEMUMachine pc_q35_machine_v1_6 = {
>      .name = "pc-q35-1.6",
>      .init = pc_q35_init_1_6,
>      .compat_props = (GlobalProperty[]) {
> -        PC_Q35_COMPAT_1_6,
> +        PC_COMPAT_1_6,
>          { /* end of list */ }
>      },
>  };
> @@ -395,7 +395,7 @@ static QEMUMachine pc_q35_machine_v1_5 = {
>      .name = "pc-q35-1.5",
>      .init = pc_q35_init_1_5,
>      .compat_props = (GlobalProperty[]) {
> -        PC_Q35_COMPAT_1_5,
> +        PC_COMPAT_1_5,
>          { /* end of list */ }
>      },
>  };
> @@ -409,7 +409,7 @@ static QEMUMachine pc_q35_machine_v1_4 = {
>      .name = "pc-q35-1.4",
>      .init = pc_q35_init_1_4,
>      .compat_props = (GlobalProperty[]) {
> -        PC_Q35_COMPAT_1_4,
> +        PC_COMPAT_1_4,
>          { /* end of list */ }
>      },
>  };
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 1331d5a..1c0c382 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -294,43 +294,6 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t);
>  int e820_get_num_entries(void);
>  bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
>  
> -#define PC_Q35_COMPAT_2_0 \
> -        PC_COMPAT_2_0, \
> -        {\
> -            .driver   = "ICH9-LPC",\
> -            .property = "memory-hotplug-support",\
> -            .value    = "off",\
> -        },{\
> -            .driver   = "xio3130-downstream",\
> -            .property = COMPAT_PROP_PCP,\
> -            .value    = "off",\
> -        },{\
> -            .driver   = "ioh3420",\
> -            .property = COMPAT_PROP_PCP,\
> -            .value    = "off",\
> -        }
> - 
> -#define PC_Q35_COMPAT_1_7 \
> -        PC_COMPAT_1_7, \
> -        PC_Q35_COMPAT_2_0, \
> -        {\
> -            .driver   = "hpet",\
> -            .property = HPET_INTCAP,\
> -            .value    = stringify(4),\
> -        }
> -
> -#define PC_Q35_COMPAT_1_6 \
> -        PC_COMPAT_1_6, \
> -        PC_Q35_COMPAT_1_7
> -
> -#define PC_Q35_COMPAT_1_5 \
> -        PC_COMPAT_1_5, \
> -        PC_Q35_COMPAT_1_6
> -
> -#define PC_Q35_COMPAT_1_4 \
> -        PC_COMPAT_1_4, \
> -        PC_Q35_COMPAT_1_5
> -
>  #define PC_COMPAT_2_0 \
>          {\
>              .driver   = "virtio-scsi-pci",\
> @@ -370,6 +333,19 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
>              .driver   = "virtio-net-pci",\
>              .property = "guest_announce",\
>              .value    = "off",\
> +        },\
> +        {\
> +            .driver   = "ICH9-LPC",\
> +            .property = "memory-hotplug-support",\
> +            .value    = "off",\
> +        },{\
> +            .driver   = "xio3130-downstream",\
> +            .property = COMPAT_PROP_PCP,\
> +            .value    = "off",\
> +        },{\
> +            .driver   = "ioh3420",\
> +            .property = COMPAT_PROP_PCP,\
> +            .value    = "off",\
>          }
>  
>  #define PC_COMPAT_1_7 \
> @@ -383,6 +359,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
>              .driver   = "PIIX4_PM",\
>              .property = "acpi-pci-hotplug-with-bridge-support",\
>              .value    = "off",\
> +        },\
> +        {\
> +            .driver   = "hpet",\
> +            .property = HPET_INTCAP,\
> +            .value    = stringify(4),\
>          }
>  
>  #define PC_COMPAT_1_6 \
> -- 
> 1.9.3