Re: [PATCH v5 1/2] dax: introduce CONFIG_DAX_DRIVER

[Dan Williams]

On Thu, Sep 28, 2017 at 11:11 PM, Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
> Dan Williams <dan.j.williams@xxxxxxxxx> writes:
>
>> In support of allowing device-mapper to compile out idle/dead code when
>> there are no dax providers in the system, introduce the DAX_DRIVER
>> symbol. This is selected by all leaf drivers that device-mapper might be
>> layered on top. This allows device-mapper to conditionally 'select DAX'
>> only when a provider is present.
>>
>> Cc: Paul Mackerras <paulus@xxxxxxxxx>
>> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
>> Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
>> Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
>> Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
>> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
>> Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
>> Cc: Bart Van Assche <Bart.VanAssche@xxxxxxx>
>> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
>> ---
>>  arch/powerpc/platforms/Kconfig |    1 +
>>  drivers/block/Kconfig          |    1 +
>>  drivers/dax/Kconfig            |    4 +++-
>>  drivers/nvdimm/Kconfig         |    1 +
>>  drivers/s390/block/Kconfig     |    1 +
>>  5 files changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/platforms/Kconfig b/arch/powerpc/platforms/Kconfig
>> index 4fd64d3f5c44..4561340c1f92 100644
>> --- a/arch/powerpc/platforms/Kconfig
>> +++ b/arch/powerpc/platforms/Kconfig
>> @@ -296,6 +296,7 @@ config AXON_RAM
>>       tristate "Axon DDR2 memory device driver"
>>       depends on PPC_IBM_CELL_BLADE && BLOCK
>>       select DAX
>> +     select DAX_DRIVER
>
>
> I would have thought you'd want to replace the select of DAX with
> a select of DAX_DRIVER?

Me too ;-)

> With the driver selecting both there's no need for the core to select
> DAX, because all the DAX drivers have done it already.

Thanks, yes, I'll fix that up.