Re: [dpdk-dev] [BUG] ixgbe vector cannot compile without bulk alloc

[Bruce Richardson <bruce.richardson@intel.com>]

On Thu, Jan 29, 2015 at 11:18:01PM +0100, Thomas Monjalon wrote:
> 2014-12-01 18:22, Thomas Monjalon:
> > 2014-12-01 17:18, Bruce Richardson:
> > > On Mon, Dec 01, 2014 at 06:10:18PM +0100, Thomas Monjalon wrote:
> > > > These 2 configuration options are incompatible:
> > > > 	CONFIG_RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC=n
> > > > 	CONFIG_RTE_IXGBE_INC_VECTOR=y
> > > > Building this config gives this error:
> > > > 	lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c:69:24:
> > > > 	error: ‘struct igb_rx_queue’ has no member named ‘fake_mbuf’
> > > > 
> > > > I'd like a confirmation that it will be always incompatible.
> > > > Thanks
> > > 
> > > Hi Thomas,
> > > 
> > > I don't think these options should always be incompatible, though as you point
> > > out you do need to turn on bulk alloc support in order to use the vector PMD.
> > > Why do you ask? There are no immediate plans to remove the dependency on our end.
> 
> So you confirm that the ixgbe vpmd really needs Rx bulk alloc and this kind of
> patch cannot work at all (I don't know the design of vpmd):
> 
> --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> @@ -2119,12 +2119,12 @@ ixgbe_reset_rx_queue(struct igb_rx_queue *rxq)
>                 rxq->rx_ring[i] = zeroed_desc;
>         }
>  
> -#ifdef RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC
>         /*
>          * initialize extra software ring entries. Space for these extra
>          * entries is always allocated
>          */
>         memset(&rxq->fake_mbuf, 0x0, sizeof(rxq->fake_mbuf));
> +#ifdef RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC
>         for (i = 0; i < RTE_PMD_IXGBE_RX_MAX_BURST; ++i) {
>                 rxq->sw_ring[rxq->nb_rx_desc + i].mbuf = &rxq->fake_mbuf;
>         }
> --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
> +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
> @@ -127,9 +127,9 @@ struct igb_rx_queue {
>         uint8_t             crc_len;  /**< 0 if CRC stripped, 4 otherwise. */
>         uint8_t             drop_en;  /**< If not 0, set SRRCTL.Drop_En. */
>         uint8_t             rx_deferred_start; /**< not in global dev start. */
> -#ifdef RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC
>         /** need to alloc dummy mbuf, for wraparound when scanning hw ring */
>         struct rte_mbuf fake_mbuf;
> +#ifdef RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC
>         /** hold packets to return to application */
>         struct rte_mbuf *rx_stage[RTE_PMD_IXGBE_RX_MAX_BURST*2];
>  #endif
> 
> > I think the compilation shouldn't fail without a proper message.
> > In order to distinguish a real compilation error from an incompatibility,
> > we should add a warning in the makefile.
> > Ideally, the build system should handle dependencies. But waiting this ideal
> > time, a warning would be graceful.
> 
> Do you agree that something like this would be OK?
> 
> --- a/lib/librte_pmd_ixgbe/Makefile
> +++ b/lib/librte_pmd_ixgbe/Makefile
> @@ -114,4 +114,8 @@ DEPDIRS-$(CONFIG_RTE_LIBRTE_IXGBE_PMD) += lib/librte_eal lib/librte_ether
>  DEPDIRS-$(CONFIG_RTE_LIBRTE_IXGBE_PMD) += lib/librte_mempool lib/librte_mbuf
>  DEPDIRS-$(CONFIG_RTE_LIBRTE_IXGBE_PMD) += lib/librte_net lib/librte_malloc
>  
> +ifeq ($(CONFIG_RTE_IXGBE_INC_VECTOR)$(CONFIG_RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC),yn)
> +$(error The ixgbe vpmd depends on Rx bulk alloc)
> +endif
> +
>  include $(RTE_SDK)/mk/rte.lib.mk
> 

Something like the above looks like a good solution to me.

/Bruce

> Thanks
> -- 
> Thomas