Re: [dpdk-dev] [PATCH v7 2/9] eal: introduce RTE common initialization level

[Thomas Monjalon <thomas@monjalon.net>]

20/07/2020 18:21, Ferruh Yigit:
> On 7/17/2020 2:49 PM, Parav Pandit wrote:
> > Currently mlx5_common uses CLASS priority to initialize
> > common code before initializing the PMD.
> > However mlx5_common is not really a class, it is the pre-initialization
> > code needed for the PMDs.
> > 
> > In subsequent patch a needed initialization sequence is:
> > (a) Initialize bus (say pci)
> > (b) Initialize common code of a driver (mlx5_common)
> > (c) Register mlx5 class PMDs (mlx5 net, mlx5 vdpa)
> > Information registered by these PMDs is used by mlx5_bus_pci PMD.
> > This mlx5 class PMDs should not confused with rte_class.
> > (d) Register mlx5 PCI bus PMD
> > 
> > Hence, introduce a new RTE priority level RTE_PRIO_COMMON which
> > can be used for common initialization and RTE_PRIO_CLASS by mlx5 PMDs
> > for class driver initialization.
> > 
> > Signed-off-by: Parav Pandit <parav@mellanox.com>
> > Acked-by: Matan Azrad <matan@mellanox.com>
> > ---
> > Changelog:
> > v2->v3:
> >  - new patch
> > ---
> >  lib/librte_eal/include/rte_common.h | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/lib/librte_eal/include/rte_common.h b/lib/librte_eal/include/rte_common.h
> > index 8f487a563..522afe58e 100644
> > --- a/lib/librte_eal/include/rte_common.h
> > +++ b/lib/librte_eal/include/rte_common.h
> > @@ -135,6 +135,7 @@ typedef uint16_t unaligned_uint16_t;
> >  
> >  #define RTE_PRIORITY_LOG 101
> >  #define RTE_PRIORITY_BUS 110
> > +#define RTE_PRIORITY_COMMON 119
> >  #define RTE_PRIORITY_CLASS 120
> >  #define RTE_PRIORITY_LAST 65535
> >  
> > 
> 
> I guess the name "common" selected because of the intention to use it by the
> common piece of the driver, but only from eal perspective the name
> "PRIORITY_COMMON" looks so vague, it doesn't describe any purpose.

You're right.

> Also the value doesn't leave any gap between the class priority, what else can
> be needed in the future in between, right?

And we can imagine a bus requiring a common lib
to be initialized before.

> @Thomas, @David, I am reluctant to get this eal change through the next-net, can
> you please review/ack it first?

What about skipping this patch and using "RTE_PRIORITY_CLASS - 1"
in the code?