Re: [Qemu-devel] [Qemu-ppc] [PATCH v2] Introduce machine specific default memory size

[Alexander Graf <agraf@suse.de>]

On 04.03.15 12:18, Nikunj A Dadhania wrote:
> QEMU default memory of 128MB is not enough to boot sPAPR
> guest. Introduce a member in the machine class to override the default
> memory size enforced by QEMU.
> 
> Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
> ---
>  hw/ppc/spapr.c         | 1 +
>  include/hw/boards.h    | 1 +
>  include/hw/ppc/spapr.h | 3 +++
>  vl.c                   | 9 +++++++++
>  4 files changed, 14 insertions(+)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 23cde20..f6b1137 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1738,6 +1738,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
>      mc->max_cpus = MAX_CPUS;
>      mc->no_parallel = 1;
>      mc->default_boot_order = NULL;
> +    mc->default_ram_size = SPAPR_DEFAULT_RAM_SIZE;
>      mc->kvm_type = spapr_kvm_type;
>      mc->has_dynamic_sysbus = true;
>  
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index 3ddc449..b2b4698 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -108,6 +108,7 @@ 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/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 716bff4..d401dd0 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -444,6 +444,9 @@ int spapr_rtas_device_tree_setup(void *fdt, hwaddr rtas_addr,
>  #define SPAPR_VIO_BASE_LIOBN    0x00000000
>  #define SPAPR_PCI_BASE_LIOBN    0x80000000
>  
> +/* Default to 1GB guest ram_size */
> +#define SPAPR_DEFAULT_RAM_SIZE  (1ULL << 30)
> +
>  #define RTAS_ERROR_LOG_MAX      2048
>  
>  typedef struct sPAPRTCETable sPAPRTCETable;
> diff --git a/vl.c b/vl.c
> index 801d487..447b993 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -2649,6 +2649,7 @@ static void set_memory_options(uint64_t *ram_slots, ram_addr_t *maxram_size)
>      const ram_addr_t default_ram_size = (ram_addr_t)DEFAULT_RAM_SIZE *
>                                          1024 * 1024;
>      QemuOpts *opts = qemu_find_opts_singleton("memory");
> +    MachineClass *machine_class;
>  
>      sz = 0;
>      mem_str = qemu_opt_get(opts, "size");
> @@ -2684,6 +2685,14 @@ static void set_memory_options(uint64_t *ram_slots, ram_addr_t *maxram_size)
>          exit(EXIT_FAILURE);
>      }
>  
> +    machine_class = find_default_machine();
> +    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
> +        fprintf(stderr, "qemu: %s guest ram size defaulting to %ld MB\n",
> +                machine_class->name,
> +                machine_class->default_ram_size / (1024 * 1024));
> +        ram_size = machine_class->default_ram_size;

Can't the check happen at the same spot that the current 128MB default
gets set?

Also, why so complicated? Just have a default value of 128MB in the
default machine class and just override it from the sPAPR one. Then
unconditionally set ram_size = mc->default_ram_size in the code that
today sets ram_size = 128MB.


Alex

> +    }
> +
>      /* store value for the future use */
>      qemu_opt_set_number(opts, "size", ram_size, &error_abort);
>      *maxram_size = ram_size;
>