It is inititally 0, so setting it to 0 should be allowed, too.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/mem/nvdimm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c
index db7d8c3050..df7646488b 100644
--- a/hw/mem/nvdimm.c
+++ b/hw/mem/nvdimm.c
@@ -52,9 +52,9 @@ static void nvdimm_set_label_size(Object *obj, Visitor *v, const char *name,
     if (local_err) {
         goto out;
     }
-    if (value < MIN_NAMESPACE_LABEL_SIZE) {
+    if (value && value < MIN_NAMESPACE_LABEL_SIZE) {
         error_setg(&local_err, "Property '%s.%s' (0x%" PRIx64 ") is required"
-                   " at least 0x%lx", object_get_typename(obj),
+                   " either 0 or at least 0x%lx", object_get_typename(obj),
                    name, value, MIN_NAMESPACE_LABEL_SIZE);
         goto out;
     }
-- 
2.17.1

On 06/15/18 16:04, David Hildenbrand wrote:
> It is inititally 0, so setting it to 0 should be allowed, too.

I'm fine with this change and believe nothing is broken in practice,
but what is expected by the user who sets a zero label size?

Look at nvdimm_dsm_device() which enables label DSMs only if the label
size is not smaller than 128 KB. If a user sets a zero label size
explicitly, does he/she expect those label DSMs are available in
guest?  (according to Intel spec, the minimal label size is 128
KBytes)

I think if it's allowed to set a zero label-size, it would be better
to document its difference from other non-zero values in docs/nvdimm.txt.

Thanks,
Haozhong

> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  hw/mem/nvdimm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c
> index db7d8c3050..df7646488b 100644
> --- a/hw/mem/nvdimm.c
> +++ b/hw/mem/nvdimm.c
> @@ -52,9 +52,9 @@ static void nvdimm_set_label_size(Object *obj, Visitor *v, const char *name,
>      if (local_err) {
>          goto out;
>      }
> -    if (value < MIN_NAMESPACE_LABEL_SIZE) {
> +    if (value && value < MIN_NAMESPACE_LABEL_SIZE) {
>          error_setg(&local_err, "Property '%s.%s' (0x%" PRIx64 ") is required"
> -                   " at least 0x%lx", object_get_typename(obj),
> +                   " either 0 or at least 0x%lx", object_get_typename(obj),
>                     name, value, MIN_NAMESPACE_LABEL_SIZE);
>          goto out;
>      }
> -- 
> 2.17.1
> 
> 

On 16.06.2018 04:05, Haozhong Zhang wrote:
> On 06/15/18 16:04, David Hildenbrand wrote:
>> It is inititally 0, so setting it to 0 should be allowed, too.
> 
> I'm fine with this change and believe nothing is broken in practice,
> but what is expected by the user who sets a zero label size?

I'd say exactly the same as if not specifying a label size, because the
default is initially 0.

I remember that the user should be able to spell everything out on the
cmdline. Relying only on default values is usually not what we want.

> 
> Look at nvdimm_dsm_device() which enables label DSMs only if the label
> size is not smaller than 128 KB. If a user sets a zero label size
> explicitly, does he/she expect those label DSMs are available in
> guest?  (according to Intel spec, the minimal label size is 128
> KBytes)
> 
> I think if it's allowed to set a zero label-size, it would be better
> to document its difference from other non-zero values in docs/nvdimm.txt.

We can fixup the the documentation to to explicitly state "default is
label-size=0" and "With label-size=0 label support is disabled.".

But this will be a separate patch.

Thanks!

> 
> Thanks,
> Haozhong
> 
>>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>>  hw/mem/nvdimm.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c
>> index db7d8c3050..df7646488b 100644
>> --- a/hw/mem/nvdimm.c
>> +++ b/hw/mem/nvdimm.c
>> @@ -52,9 +52,9 @@ static void nvdimm_set_label_size(Object *obj, Visitor *v, const char *name,
>>      if (local_err) {
>>          goto out;
>>      }
>> -    if (value < MIN_NAMESPACE_LABEL_SIZE) {
>> +    if (value && value < MIN_NAMESPACE_LABEL_SIZE) {
>>          error_setg(&local_err, "Property '%s.%s' (0x%" PRIx64 ") is required"
>> -                   " at least 0x%lx", object_get_typename(obj),
>> +                   " either 0 or at least 0x%lx", object_get_typename(obj),
>>                     name, value, MIN_NAMESPACE_LABEL_SIZE);
>>          goto out;
>>      }
>> -- 
>> 2.17.1
>>
>>
> 


-- 

Thanks,

David / dhildenb

On Fri, 15 Jun 2018 16:04:46 +0200
David Hildenbrand <david@redhat.com> wrote:

> It is inititally 0, so setting it to 0 should be allowed, too.
I'm not sure if we need to permit it.
By default labels are disabled (label-size=0) and user are supposed to provide
this option if labels should be enabled with a valid size. 

it could be confusing for user when asking for label and not getting it.

I suggest to drop this patch, it's not really related to this series
nor required for your future work.

> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  hw/mem/nvdimm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c
> index db7d8c3050..df7646488b 100644
> --- a/hw/mem/nvdimm.c
> +++ b/hw/mem/nvdimm.c
> @@ -52,9 +52,9 @@ static void nvdimm_set_label_size(Object *obj, Visitor *v, const char *name,
>      if (local_err) {
>          goto out;
>      }
> -    if (value < MIN_NAMESPACE_LABEL_SIZE) {
> +    if (value && value < MIN_NAMESPACE_LABEL_SIZE) {
>          error_setg(&local_err, "Property '%s.%s' (0x%" PRIx64 ") is required"
> -                   " at least 0x%lx", object_get_typename(obj),
> +                   " either 0 or at least 0x%lx", object_get_typename(obj),
>                     name, value, MIN_NAMESPACE_LABEL_SIZE);
>          goto out;
>      }

On 18.06.2018 14:03, Igor Mammedov wrote:
> On Fri, 15 Jun 2018 16:04:46 +0200
> David Hildenbrand <david@redhat.com> wrote:
> 
>> It is inititally 0, so setting it to 0 should be allowed, too.
> I'm not sure if we need to permit it.
> By default labels are disabled (label-size=0) and user are supposed to provide
> this option if labels should be enabled with a valid size. 
> 
> it could be confusing for user when asking for label and not getting it.
> 
> I suggest to drop this patch, it's not really related to this series
> nor required for your future work.
> 

As I just want to finally get this stuff off my table, I agree to
whatever you say.


-- 

Thanks,

David / dhildenb