Re: [Qemu-devel] [PATCH RFC 2/4] check if we have space left for hotplugged memory

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

On Sat, Jun 14, 2014 at 12:48:57PM +0800, Hu Tao wrote:
> If pc-dimm is specified on qemu command line, but only with
> -m size (aka not -m size,maxmem,slots) then qemu will core dump.
> 
> This patch fixes the problem.
> 
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> ---
>  hw/mem/pc-dimm.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
> index 8c26568..6e8bf43 100644
> --- a/hw/mem/pc-dimm.c
> +++ b/hw/mem/pc-dimm.c
> @@ -107,7 +107,12 @@ uint64_t pc_dimm_get_free_addr(uint64_t address_space_start,
>      uint64_t new_addr, ret = 0;
>      uint64_t address_space_end = address_space_start + address_space_size;
>  
> -    assert(address_space_end > address_space_size);
> +    if (address_space_size == 0) {
> +        error_setg(errp, "can't add memory beyond 0x%" PRIx64,
> +                   address_space_end);

That's quite an unfriendly error message, isn't it?
Why not explain what the problem is to the user?

> +        goto out;
> +    }
> +

I would move the assert to this point. It protects against
integer overflow.

>      object_child_foreach(qdev_get_machine(), pc_dimm_built_list, &list);
>  
>      if (hint) {


> -- 
> 1.9.3