Re: [Qemu-devel] [PATCH v2] pc: ACPI BIOS: use highest NUMA node for hotplug mem hole SRAT entry

[Igor Mammedov]

On Thu, 25 May 2017 09:07:47 +0200
Ladi Prosek <address@hidden> wrote:

> For reasons unknown, Windows won't online all memory, both at command
> line and hot-plugged later, unless the hotplug mem hole SRAT entry
> specifies a node greater than or equal to the ones where memory is
> added.
> 
> Using the highest node on the machine makes recent versions of Windows
> happy.
> 
> With this example command line:
>   ... \
>   -m 1024,slots=4,maxmem=32G \
>   -numa node,nodeid=0 \
>   -numa node,nodeid=1 \
>   -numa node,nodeid=2 \
>   -numa node,nodeid=3 \
>   -object memory-backend-ram,size=1G,id=mem-mem1 \
>   -device pc-dimm,id=dimm-mem1,memdev=mem-mem1,node=1
> 
> Windows reports a total of 1G of RAM without this commit and the expected
> 2G with this commit.
> 
> Signed-off-by: Ladi Prosek <address@hidden>
Reviewed-by: Igor Mammedov <address@hidden>

> ---
> 
> note to maintainer:
> tests/acpi-test-data need to be updated due to change in SRAT table
> 
>  hw/i386/acpi-build.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index afcadac..82bd44f 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -2404,14 +2404,17 @@ build_srat(GArray *table_data, BIOSLinker *linker, 
> MachineState *machine)
>      }
>  
>      /*
> -     * Entry is required for Windows to enable memory hotplug in OS.
> +     * Entry is required for Windows to enable memory hotplug in OS
> +     * and for Linux to enable SWIOTLB when booted with less than
> +     * 4G of RAM. Windows works better if the entry sets proximity
> +     * to the highest NUMA node in the machine.
>       * Memory devices may override proximity set by this entry,
>       * providing _PXM method if necessary.
>       */
>      if (hotplugabble_address_space_size) {
>          numamem = acpi_data_push(table_data, sizeof *numamem);
>          build_srat_memory(numamem, pcms->hotplug_memory.base,
> -                          hotplugabble_address_space_size, 0,
> +                          hotplugabble_address_space_size, pcms->numa_nodes 
> - 1,
>                            MEM_AFFINITY_HOTPLUGGABLE | MEM_AFFINITY_ENABLED);
>      }
>