Linux Virtualization - Sep 2020 - [PATCH v3 -next] vdpa: mlx5: change Kconfig depends to fix build errors

On 9/24/20 3:24 AM, Eli Cohen wrote:
> On Thu, Sep 24, 2020 at 05:30:55AM -0400, Michael S. Tsirkin wrote:
>>>> --- linux-next-20200917.orig/drivers/vdpa/Kconfig
>>>> +++ linux-next-20200917/drivers/vdpa/Kconfig
>>>> @@ -31,7 +31,7 @@ config IFCVF
>>>>
>>>>  config MLX5_VDPA
>>>>  	bool "MLX5 VDPA support library for ConnectX
devices"
>>>> -	depends on MLX5_CORE
>>>> +	depends on VHOST_IOTLB && MLX5_CORE
>>>>  	default n
>>>
>>> While we are here, can anyone who apply this patch delete the
"default n" line?
>>> It is by default "n".
> 
> I can do that
> 
>>>
>>> Thanks
>>
>> Hmm other drivers select VHOST_IOTLB, why not do the same?
v1 used select, but Saeed requested use of depends instead because
select can cause problems.
> I can't see another driver doing that. Perhaps I can set dependency on
> VHOST which by itself depends on VHOST_IOTLB?
>>
>>
>>>>  	help
>>>>  	  Support library for Mellanox VDPA drivers. Provides code
that is
>>>>
>>

-- 
~Randy

On Thu, Sep 24, 2020 at 08:47:05AM -0700, Randy Dunlap
wrote:
> On 9/24/20 3:24 AM, Eli Cohen wrote:
> > On Thu, Sep 24, 2020 at 05:30:55AM -0400, Michael S. Tsirkin wrote:
> >>>> --- linux-next-20200917.orig/drivers/vdpa/Kconfig
> >>>> +++ linux-next-20200917/drivers/vdpa/Kconfig
> >>>> @@ -31,7 +31,7 @@ config IFCVF
> >>>>
> >>>>  config MLX5_VDPA
> >>>>  	bool "MLX5 VDPA support library for ConnectX
devices"
> >>>> -	depends on MLX5_CORE
> >>>> +	depends on VHOST_IOTLB && MLX5_CORE
> >>>>  	default n
> >>>
> >>> While we are here, can anyone who apply this patch delete the
"default n" line?
> >>> It is by default "n".
> > 
> > I can do that
> > 
> >>>
> >>> Thanks
> >>
> >> Hmm other drivers select VHOST_IOTLB, why not do the same?
> 
> v1 used select, but Saeed requested use of depends instead because
> select can cause problems.
> 
> > I can't see another driver doing that. Perhaps I can set
dependency on
> > VHOST which by itself depends on VHOST_IOTLB?
> >>
> >>
> >>>>  	help
> >>>>  	  Support library for Mellanox VDPA drivers. Provides
code that is
> >>>>
> >>
> 
Saeed what kind of problems? It's used with select in other places,
isn't it?
> -- 
> ~Randy

On Fri, Sep 25, 2020 at 10:20:05AM +0300, Leon Romanovsky
wrote:
> On Thu, Sep 24, 2020 at 12:02:43PM -0400, Michael S. Tsirkin wrote:
> > On Thu, Sep 24, 2020 at 08:47:05AM -0700, Randy Dunlap wrote:
> > > On 9/24/20 3:24 AM, Eli Cohen wrote:
> > > > On Thu, Sep 24, 2020 at 05:30:55AM -0400, Michael S. Tsirkin
wrote:
> > > >>>> ---
linux-next-20200917.orig/drivers/vdpa/Kconfig
> > > >>>> +++ linux-next-20200917/drivers/vdpa/Kconfig
> > > >>>> @@ -31,7 +31,7 @@ config IFCVF
> > > >>>>
> > > >>>>  config MLX5_VDPA
> > > >>>>  	bool "MLX5 VDPA support library for
ConnectX devices"
> > > >>>> -	depends on MLX5_CORE
> > > >>>> +	depends on VHOST_IOTLB && MLX5_CORE
> > > >>>>  	default n
> > > >>>
> > > >>> While we are here, can anyone who apply this patch
delete the "default n" line?
> > > >>> It is by default "n".
> > > >
> > > > I can do that
> > > >
> > > >>>
> > > >>> Thanks
> > > >>
> > > >> Hmm other drivers select VHOST_IOTLB, why not do the
same?
> > >
> > > v1 used select, but Saeed requested use of depends instead
because
> > > select can cause problems.
> > >
> > > > I can't see another driver doing that. Perhaps I can set
dependency on
> > > > VHOST which by itself depends on VHOST_IOTLB?
> > > >>
> > > >>
> > > >>>>  	help
> > > >>>>  	  Support library for Mellanox VDPA drivers.
Provides code that is
> > > >>>>
> > > >>
> > >
> >
> > Saeed what kind of problems? It's used with select in other
places,
> > isn't it?
> 
> IMHO, "depends" is much more explicit than "select".
> 
> Thanks
This is now how VHOST_IOTLB has been designed though.
If you want to change VHOST_IOTLB to depends I think
we should do it consistently all over.


config VHOST_IOTLB
        tristate
        help
          Generic IOTLB implementation for vhost and vringh.
          This option is selected by any driver which needs to support
          an IOMMU in software.

> >
> > > --
> > > ~Randy
> >

On 2020/9/25 ??6:19, Michael S. Tsirkin wrote:
> On Fri, Sep 25, 2020 at 10:20:05AM +0300, Leon Romanovsky wrote:
>> On Thu, Sep 24, 2020 at 12:02:43PM -0400, Michael S. Tsirkin wrote:
>>> On Thu, Sep 24, 2020 at 08:47:05AM -0700, Randy Dunlap wrote:
>>>> On 9/24/20 3:24 AM, Eli Cohen wrote:
>>>>> On Thu, Sep 24, 2020 at 05:30:55AM -0400, Michael S.
Tsirkin wrote:
>>>>>>>> ---
linux-next-20200917.orig/drivers/vdpa/Kconfig
>>>>>>>> +++ linux-next-20200917/drivers/vdpa/Kconfig
>>>>>>>> @@ -31,7 +31,7 @@ config IFCVF
>>>>>>>>
>>>>>>>>   config MLX5_VDPA
>>>>>>>>   	bool "MLX5 VDPA support library for
ConnectX devices"
>>>>>>>> -	depends on MLX5_CORE
>>>>>>>> +	depends on VHOST_IOTLB && MLX5_CORE
>>>>>>>>   	default n
>>>>>>> While we are here, can anyone who apply this patch
delete the "default n" line?
>>>>>>> It is by default "n".
>>>>> I can do that
>>>>>
>>>>>>> Thanks
>>>>>> Hmm other drivers select VHOST_IOTLB, why not do the
same?
>>>> v1 used select, but Saeed requested use of depends instead
because
>>>> select can cause problems.
>>>>
>>>>> I can't see another driver doing that. Perhaps I can
set dependency on
>>>>> VHOST which by itself depends on VHOST_IOTLB?
>>>>>>
>>>>>>>>   	help
>>>>>>>>   	  Support library for Mellanox VDPA drivers.
Provides code that is
>>>>>>>>
>>> Saeed what kind of problems? It's used with select in other
places,
>>> isn't it?
>> IMHO, "depends" is much more explicit than
"select".
>>
>> Thanks
> This is now how VHOST_IOTLB has been designed though.
> If you want to change VHOST_IOTLB to depends I think
> we should do it consistently all over.
>
>
> config VHOST_IOTLB
>          tristate
>          help
>            Generic IOTLB implementation for vhost and vringh.
>            This option is selected by any driver which needs to support
>            an IOMMU in software.

Yes, since there's no prompt for VHOST_IOTLB which means, if there's no 
other symbol that select VHOST_IOTLB, you can't enable MLX5 at all.

See kconfig-language.rst:


 ??? In general use select only for non-visible symbols
 ??? (no prompts anywhere) and for symbols with no dependencies.
 ??? That will limit the usefulness but on the other hand avoid
 ??? the illegal configurations all over.

Thanks

>
>
>>>> --
>>>> ~Randy

On Thu, Sep 24, 2020 at 08:47:05AM -0700, Randy Dunlap
wrote:
> On 9/24/20 3:24 AM, Eli Cohen wrote:
> > On Thu, Sep 24, 2020 at 05:30:55AM -0400, Michael S. Tsirkin wrote:
> >>>> --- linux-next-20200917.orig/drivers/vdpa/Kconfig
> >>>> +++ linux-next-20200917/drivers/vdpa/Kconfig
> >>>> @@ -31,7 +31,7 @@ config IFCVF
> >>>>
> >>>>  config MLX5_VDPA
> >>>>  	bool "MLX5 VDPA support library for ConnectX
devices"
> >>>> -	depends on MLX5_CORE
> >>>> +	depends on VHOST_IOTLB && MLX5_CORE
> >>>>  	default n
> >>>
> >>> While we are here, can anyone who apply this patch delete the
"default n" line?
> >>> It is by default "n".
> > 
> > I can do that
> > 
> >>>
> >>> Thanks
> >>
> >> Hmm other drivers select VHOST_IOTLB, why not do the same?
> 
> v1 used select, but Saeed requested use of depends instead because
> select can cause problems.
OK I went over the history. v1 selected VHOST, that as the issue I think.
A later version switched to VHOST_IOTLB, that is ok to select.
> > I can't see another driver doing that. Perhaps I can set
dependency on
> > VHOST which by itself depends on VHOST_IOTLB?
> >>
> >>
> >>>>  	help
> >>>>  	  Support library for Mellanox VDPA drivers. Provides
code that is
> >>>>
> >>
> 
> 
> -- 
> ~Randy