Re: [Qemu-devel] [PATCH 33/35] pc: ACPI BIOS: reserve SRAT entry for hotplug mem hole

[Hu Tao]

On Fri, Apr 04, 2014 at 03:36:58PM +0200, Igor Mammedov wrote:
> Needed for Windows to use hotplugged memory device, otherwise
> it complains that server is not configured for memory hotplug.
> Tests shows that aftewards it uses dynamically provided
> proximity value from _PXM() method if available.
> 
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
>  hw/i386/acpi-build.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index ef89e99..012b100 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1197,6 +1197,8 @@ build_srat(GArray *table_data, GArray *linker,
>      uint64_t curnode;
>      int srat_start, numa_start, slots;
>      uint64_t mem_len, mem_base, next_base;
> +    PCMachineState *pcms = PC_MACHINE(qdev_get_machine());
> +    ram_addr_t hotplug_as_size = memory_region_size(&pcms->hotplug_memory);
>  
>      srat_start = table_data->len;
>  
> @@ -1261,6 +1263,18 @@ build_srat(GArray *table_data, GArray *linker,
>          acpi_build_srat_memory(numamem, 0, 0, 0, MEM_AFFINITY_NOFLAGS);
>      }
>  
> +    /*
> +     * Fake entry required by Windows to enable memory hotplug in OS.
> +     * Individual DIMM devices override proximity set here via _PXM method,
> +     * which returns associated with it NUMA node id.
> +     */
> +    if (hotplug_as_size) {
> +        numamem = acpi_data_push(table_data, sizeof *numamem);
> +        acpi_build_srat_memory(numamem, pcms->hotplug_memory_base,
> +                               hotplug_as_size, 0, MEM_AFFINITY_HOTPLUGGABLE 
> |
> +                               MEM_AFFINITY_ENABLED);
> +    }
> +

Hi Igor,

With the faked entry, memory unplug doesn't work. Entries should be set
up for each node with correct flags(enable, hotpluggable) to make memory
unplug work.

Windows has not been tested yet. I encountered a problem that there is
no SRAT in Windows so even memory hotplug doesn't work. (but there is
in Linux with the same configuration).

Regards,
Hu Tao