Re: [Qemu-devel] [PATCH 1/2] smbios: Fix dimm size calculation when RAM is multiple of 16GB

[Paolo Bonzini <pbonzini@redhat.com>]

On 07/01/2015 18:36, Eduardo Habkost wrote:
> The Memory Device size calculation logic is broken when the RAM size is
> a multiple of 16GB, making the size of the last entry be 0 instead of
> 16GB. Fix the logic to handle that case correctly.
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>  hw/i386/smbios.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/i386/smbios.c b/hw/i386/smbios.c
> index 024e594..ae7032a 100644
> --- a/hw/i386/smbios.c
> +++ b/hw/i386/smbios.c
> @@ -850,7 +850,8 @@ void smbios_get_tables(uint8_t **tables, size_t *tables_len,
>          }
>  
>  #define MAX_DIMM_SZ (16ll * ONE_GB)
> -#define GET_DIMM_SZ ((i < dimm_cnt - 1) ? MAX_DIMM_SZ : ram_size % MAX_DIMM_SZ)
> +#define GET_DIMM_SZ ((i < dimm_cnt - 1) ? MAX_DIMM_SZ \
> +                                        : ((ram_size - 1) % MAX_DIMM_SZ) + 1)
>  
>          dimm_cnt = QEMU_ALIGN_UP(ram_size, MAX_DIMM_SZ) / MAX_DIMM_SZ;

Using "dimm_size = MAX(ram_size, MAX_DIMM_SZ); ram_size -= dimm_size"
would have been less weird, but the whole code here is interesting so
your patch is just keeping with the style.  We all do that. :)

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>