Re: [Qemu-devel] [PATCH v8 12/18] hw/arm/boot: Expose the PC-DIMM nodes in the DT

[Auger Eric]

Hi Igor,

On 2/26/19 6:08 PM, Igor Mammedov wrote:
> On Tue, 26 Feb 2019 14:50:08 +0100
> Eric Auger <address@hidden> wrote:
> 
>> From: Shameer Kolothum <address@hidden>
>>
>> This patch adds memory nodes corresponding to PC-DIMM regions.
>>
>> NVDIMM and ACPI_NVDIMM configs are not yet set for ARM so we
>> don't need to care about NVDIMM at this stage.
>>
>> Signed-off-by: Shameer Kolothum <address@hidden>
>> Signed-off-by: Eric Auger <address@hidden>
>> Reviewed-by: Igor Mammedov <address@hidden>
> I'm having second thoughts on this one,
> maybe we should drop this patch or at least not to do this by default.
See my reply on your cover letter remark.
> In the later case it would mean some kind of property that user could use
> to turn this on which in its own turn adds more clutter to user tunables
> (which is not desirable). So I'm leaning more towards dropping this patch for 
> now.
So what about DT support? Doesn't it make sense to support
cold-pluggable DIMMS?

Thanks

Eric
> 
>>
>> ---
>> v7 -> v8:
>> - s/NV_DIMM/NVDIMM
>> - fix indent
>> v6 -> v7:
>> - rework the error messages, use a switch/case
>> v3 -> v4:
>> - git rid of @base and @len in fdt_add_hotpluggable_memory_nodes
>>
>> v1 -> v2:
>> - added qapi_free_MemoryDeviceInfoList and simplify the loop
>> ---
>>  hw/arm/boot.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 42 insertions(+)
>>
>> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
>> index a830655e1a..4caaf91583 100644
>> --- a/hw/arm/boot.c
>> +++ b/hw/arm/boot.c
>> @@ -19,6 +19,7 @@
>>  #include "sysemu/numa.h"
>>  #include "hw/boards.h"
>>  #include "hw/loader.h"
>> +#include "hw/mem/memory-device.h"
>>  #include "elf.h"
>>  #include "sysemu/device_tree.h"
>>  #include "qemu/config-file.h"
>> @@ -522,6 +523,41 @@ static void fdt_add_psci_node(void *fdt)
>>      qemu_fdt_setprop_cell(fdt, "/psci", "migrate", migrate_fn);
>>  }
>>  
>> +static int fdt_add_hotpluggable_memory_nodes(void *fdt,
>> +                                             uint32_t acells, uint32_t 
>> scells) {
>> +    MemoryDeviceInfoList *info, *info_list = qmp_memory_device_list();
>> +    MemoryDeviceInfo *mi;
>> +    int ret = 0;
>> +
>> +    for (info = info_list; info != NULL; info = info->next) {
>> +        mi = info->value;
>> +        switch (mi->type) {
>> +        case MEMORY_DEVICE_INFO_KIND_DIMM:
>> +        {
>> +            PCDIMMDeviceInfo *di = mi->u.dimm.data;
>> +
>> +            ret = fdt_add_memory_node(fdt, acells, di->addr,
>> +                                      scells, di->size, di->node);
>> +            if (ret) {
>> +                fprintf(stderr,
>> +                        "couldn't add PCDIMM /address@hidden"PRIx64" 
>> node\n",
>> +                        di->addr);
>> +                goto out;
>> +            }
>> +            break;
>> +        }
>> +        default:
>> +            fprintf(stderr, "%s memory nodes are not yet supported\n",
>> +                    MemoryDeviceInfoKind_str(mi->type));
>> +            ret = -ENOENT;
>> +            goto out;
>> +        }
>> +    }
>> +out:
>> +    qapi_free_MemoryDeviceInfoList(info_list);
>> +    return ret;
>> +}
>> +
>>  int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
>>                   hwaddr addr_limit, AddressSpace *as)
>>  {
>> @@ -621,6 +657,12 @@ int arm_load_dtb(hwaddr addr, const struct 
>> arm_boot_info *binfo,
>>          }
>>      }
>>  
>> +    rc = fdt_add_hotpluggable_memory_nodes(fdt, acells, scells);
>> +    if (rc < 0) {
>> +        fprintf(stderr, "couldn't add hotpluggable memory nodes\n");
>> +        goto fail;
>> +    }
>> +
>>      rc = fdt_path_offset(fdt, "/chosen");
>>      if (rc < 0) {
>>          qemu_fdt_add_subnode(fdt, "/chosen");
>