Re: [Qemu-devel] [PATCH 4/7] spapr: Split memory nodes to power-of-two blocks

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 06/16/2014 05:53 PM, Alexey Kardashevskiy wrote:
> Linux kernel expects nodes to have power-of-two size and
> does WARN_ON if this is not the case:
> [    0.041052] devtmpfs: initialized
> [    0.041292] ------------[ cut here ]------------
> [    0.041456] WARNING: at drivers/base/memory.c:115
> 
> This splits memory nodes into set of smaller blocks with
> a size which is a power of two. This makes sure the start
> address of every node is aligned to the node size.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>  hw/ppc/spapr.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 666b676..10202e2 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -710,8 +710,18 @@ static int spapr_populate_memory(sPAPREnvironment *spapr, void *fdt)
>              mem_start += spapr->rma_size;
>              node_size -= spapr->rma_size;
>          }
> -        spapr_populate_memory_node(fdt, i, mem_start, node_size);
> -        mem_start += node_size;
> +        for ( ; node_size; ) {
> +            hwaddr sizetmp = pow2floor(node_size);
> +
> +            /* mem_start != 0 here */
> +            if (ffs(mem_start) < ffs(sizetmp)) {
> +                sizetmp = MIN(sizetmp, 1 << (ffs(mem_start) - 1));


And I do not need MIN() here. Uff.


> +            }
> +
> +            spapr_populate_memory_node(fdt, i, mem_start, sizetmp);
> +            node_size -= sizetmp;
> +            mem_start += sizetmp;
> +        }
>      }
>  
>      return 0;
> 


-- 
Alexey