Re: [Qemu-devel] [PATCH v3 3/4] pc: drop memory region alignment check for 0

[Auger Eric <eric.auger@redhat.com>]

Hi David,

On 07/02/2018 11:37 AM, David Hildenbrand wrote:
> All applicable memory regions always have an alignment > 0. All memory
> backends result in file_ram_alloc() or qemu_anon_ram_alloc() getting
> called, setting the alignment to > 0.
> 
> So a PCDIMM memory region always has an alignment > 0. NVDIMM copy the
> alignment of the original memory memory region into the handcrafted memory
> region that will be used at this place.
> 
> So the check for 0 can be dropped and we can reduce the special
> handling.
> 
> Dropping this check makes factoring out of alignment handling easier as
> compat handling only has to look at pcmc->enforce_aligned_dimm and not
> care about the alignment of the memory region.
> 
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> Reviewed-by: Igor Mammedov <imammedo@redhat.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  hw/i386/pc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index bf986baf91..934b7155b1 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1712,7 +1712,7 @@ static void pc_memory_plug(HotplugHandler *hotplug_dev,
>      uint64_t align = TARGET_PAGE_SIZE;
>      bool is_nvdimm = object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM);
>  
> -    if (memory_region_get_alignment(mr) && pcmc->enforce_aligned_dimm) {
> +    if (pcmc->enforce_aligned_dimm) {
>          align = memory_region_get_alignment(mr);
>      }
>  
> 
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric