On 10/12/18 2:51 AM, Johannes Thumshirn wrote:

On 12/10/18 08:56, Dongli Zhang wrote:

quoted

Hi Jens,

Will the legacy path be fully deprecated?

In addition to performance measurement, null_blk is a very good tutorial for
beginners to understand how to implement a legacy path based block driver from
scratch. Unless legacy path is not used any longer, why not keep it in the code
as a tutorial?

But when there is no tutorial on how to write drivers for the legacy
path no one will write drivers for the legacy path and will be upset
when we remove it.

Plus the legacy path is going away right now, that's the whole point of
this series of patches. Once this is done, I'm killing all that code.

The whole point of legacy is that it's, well, legacy. Nobody should
be writing that style of driver anymore. null_blk has a clean blk-mq
implementation, that's what people can look at if they want to learn
how to write a new blk-mq driver.

-- 
Jens Axboe