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

[Marcel Apfelbaum <marcel.apfelbaum@gmail.com>]

On 03/04/2015 01:18 PM, 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>
Hi,
Thank you for contributing to QEMU!

> ---
>   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;


You add a field to MachineClass that represents default_ram_size.
That's fair because different machine types may have a different "native" default.

But in this case you should set DEFAULT_RAM_SIZE as default for all machine types
for consistency. (as suggested also by others)

>
>       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();
I am not sure this is want you want to do here.
I think you want to use the *current* machine class and not the default one.
that can be passed as parameter to set_memory_options.

> +    if (machine_class->default_ram_size && ram_size < machine_class->default_ram_size) {
and here you can drop the  un-natural machine_class->default_ram_size check

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

Thanks,
Marcel