Re: [Qemu-devel] [PATCH 14/35] pc: exit QEMU if slots > 256

[Eduardo Habkost]

On Fri, Apr 04, 2014 at 03:36:39PM +0200, Igor Mammedov wrote:
> ... which is current ACPI implementation limit.
> 
> Signed-off-by: Igor Mammedov <address@hidden>

With this we will have yet another hardcoded limit/assumption scattererd
in different places around the code, which we won't know how/if it can
be changed in the future.

I would prefer to have a #define and an explanation on the code for the
specific limit, so people know if/when/how it is safe to change it a few
years from now.

Something like:

hw/acpi/acpi.h:
    /* current device naming scheme dosen't support
     * more that 256 memory devices
     */
    #define ACPI_MAX_RAM_SLOTS 256

hw/acpi/acpi-build.c:build_ssdt():
    assert(nr_mem <= ACPI_MAX_RAM_SLOTS)

hw/i386/pc.c:
    if (machine->init_args.ram_slots > ACPI_MAX_RAM_SLOTS) {
        error_report("unsupported amount of memory slots: %"PRIu64,
                     machine->init_args.ram_slots);
        exit(EXIT_FAILURE);
    }


> ---
>  hw/i386/pc.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 69e4225..6fe1803 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1204,6 +1204,12 @@ FWCfgState *pc_memory_init(MemoryRegion *system_memory,
>          ram_addr_t hotplug_mem_size =
>              machine->init_args.maxram_size - ram_size;
>  
> +        if (machine->init_args.ram_slots > 256) {
> +            error_report("unsupported amount of memory slots: %"PRIu64,
> +                         machine->init_args.ram_slots);
> +            exit(EXIT_FAILURE);
> +        }
> +
>          pcms->hotplug_memory_base =
>              ROUND_UP(0x100000000ULL + above_4g_mem_size, 1ULL << 30);
>  
> -- 
> 1.9.0
> 

-- 
Eduardo