Re: [Qemu-devel] [PATCH v3 1/2] machine: add default_ram_size to machine class

[Igor Mammedov <imammedo@redhat.com>]

On Thu,  5 Mar 2015 14:36:10 +0530
Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:

> Machines types can have different requirement for default ram
> size. Introduce a member in the machine class and set the current
> default_ram_size to 128MB.
> 
> For QEMUMachine types override the value during the registration of
> the machine and for MachineClass introduce the generic class init
> setting the default_ram_size.
> 
> In case the user passes memory that is lesser that the default ram
> size, upscale the value to the machine's default ram size with a
> warning.
> 
> Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
> ---
>  hw/core/machine.c   |  8 ++++++++
>  include/hw/boards.h |  4 ++++
>  vl.c                | 29 +++++++++++++++++------------
>  3 files changed, 29 insertions(+), 12 deletions(-)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index fbd91be..29c48de 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -403,11 +403,19 @@ bool machine_usb(MachineState *machine)
>      return machine->usb;
>  }
>  
> +static void machine_class_init(ObjectClass *oc, void *data)
> +{
> +    MachineClass *mc = MACHINE_CLASS(oc);
> +
> +    mc->default_ram_size = MACHINE_DEFAULT_RAM_SIZE;
> +}
> +
>  static const TypeInfo machine_info = {
>      .name = TYPE_MACHINE,
>      .parent = TYPE_OBJECT,
>      .abstract = true,
>      .class_size = sizeof(MachineClass),
> +    .class_init    = machine_class_init,
>      .instance_size = sizeof(MachineState),
>      .instance_init = machine_initfn,
>      .instance_finalize = machine_finalize,
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index 3ddc449..3fca4e0 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -62,6 +62,9 @@ int qemu_register_machine(QEMUMachine *m);
>  #define MACHINE_CLASS(klass) \
>      OBJECT_CLASS_CHECK(MachineClass, (klass), TYPE_MACHINE)
>  
> +/* Default 128 MB as guest ram size */
> +#define MACHINE_DEFAULT_RAM_SIZE (1UL << 27)
no need for it to be global, bury it inside hw/core/machine.c

> +
>  MachineClass *find_default_machine(void);
>  extern MachineState *current_machine;
>  
> @@ -108,6 +111,7 @@ struct MachineClass {
>      const char *default_display;
>      GlobalProperty *compat_props;
>      const char *hw_version;
> +    ram_addr_t default_ram_size;
>  
>      HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
>                                             DeviceState *dev);
> diff --git a/vl.c b/vl.c
> index 801d487..7af1c0b 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -120,8 +120,6 @@ int main(int argc, char **argv)
>  #include "qom/object_interfaces.h"
>  #include "qapi-event.h"
>  
> -#define DEFAULT_RAM_SIZE 128
> -
>  #define MAX_VIRTIO_CONSOLES 1
>  #define MAX_SCLP_CONSOLES 1
>  
> @@ -1333,6 +1331,7 @@ static void machine_class_init(ObjectClass *oc, void *data)
Now it's confusing, we have 2 machine_class_init() one for TYPE_MACHINE
in hw/core/machine.c and another one here for subclasses.

Maybe rename this one to qemu_machine_class_init() with comment that it's
transitional class registration used for converting from legacy QEMUMachine
to MachineClass.

>      mc->is_default = qm->is_default;
>      mc->default_machine_opts = qm->default_machine_opts;
>      mc->default_boot_order = qm->default_boot_order;
> +    mc->default_ram_size = MACHINE_DEFAULT_RAM_SIZE;
this looks wrong, default_ram_size  is initialized when TYPE_MACHINE
class is initialized. No need to override the same default in immediate subclass
 

>      mc->default_display = qm->default_display;
>      mc->compat_props = qm->compat_props;
>      mc->hw_version = qm->hw_version;
> @@ -2641,13 +2640,13 @@ out:
>      return 0;
>  }
>  
> -static void set_memory_options(uint64_t *ram_slots, ram_addr_t *maxram_size)
> +static void set_memory_options(uint64_t *ram_slots, ram_addr_t *maxram_size,
> +                               MachineClass *mc)
>  {
>      uint64_t sz;
>      const char *mem_str;
>      const char *maxmem_str, *slots_str;
> -    const ram_addr_t default_ram_size = (ram_addr_t)DEFAULT_RAM_SIZE *
> -                                        1024 * 1024;
> +    const ram_addr_t default_ram_size = mc->default_ram_size;
>      QemuOpts *opts = qemu_find_opts_singleton("memory");
>  
>      sz = 0;
> @@ -2684,6 +2683,12 @@ static void set_memory_options(uint64_t *ram_slots, ram_addr_t *maxram_size)
>          exit(EXIT_FAILURE);
>      }
>  
> +    if (ram_size < default_ram_size) {
> +        fprintf(stderr, "WARNING: qemu: %s guest ram size defaulting to %ld MB\n",
> +                mc->name, default_ram_size / (1024 * 1024));
> +        ram_size = default_ram_size;
> +    }
In previous review someone explicitly asked not to override lower ram_size
if it was requested by user on command line.

> +
>      /* store value for the future use */
>      qemu_opt_set_number(opts, "size", ram_size, &error_abort);
>      *maxram_size = ram_size;
> @@ -3763,7 +3768,13 @@ int main(int argc, char **argv, char **envp)
>          machine_class = machine_parse(optarg);
>      }
>  
> -    set_memory_options(&ram_slots, &maxram_size);
> +    if (machine_class == NULL) {
> +        fprintf(stderr, "No machine specified, and there is no default.\n"
> +                "Use -machine help to list supported machines!\n");
> +        exit(1);
> +    }
> +
> +    set_memory_options(&ram_slots, &maxram_size, machine_class);
>  
>      loc_set_none();
>  
> @@ -3792,12 +3803,6 @@ int main(int argc, char **argv, char **envp)
>      }
>  #endif
>  
> -    if (machine_class == NULL) {
> -        fprintf(stderr, "No machine specified, and there is no default.\n"
> -                "Use -machine help to list supported machines!\n");
> -        exit(1);
> -    }
> -
>      current_machine = MACHINE(object_new(object_class_get_name(
>                            OBJECT_CLASS(machine_class))));
>      if (machine_help_func(qemu_get_machine_opts(), current_machine)) {