Re: [PATCH v2 1/2] ixgbe: fix build with gcc 4.4

[Vlad Zolotarov <vladz-RmZWMc9puTNJc61us3aD9laTQe2KTcn/@public.gmane.org>]

On 04/15/15 23:49, Thomas Monjalon wrote:
> With GCC 4.4.7 from CentOS 6.5, the following errors arise:
>
> lib/librte_pmd_ixgbe/ixgbe_rxtx.c: In function ‘ixgbe_dev_rx_queue_setup’:
> lib/librte_pmd_ixgbe/ixgbe_rxtx.c:2509: error: missing initializer
> lib/librte_pmd_ixgbe/ixgbe_rxtx.c:2509: error: (near initialization for ‘dev_info.driver_name’)
>
> lib/librte_pmd_ixgbe/ixgbe_rxtx.c: In function ‘ixgbe_set_rsc’:
> lib/librte_pmd_ixgbe/ixgbe_rxtx.c:4072: error: missing initializer
> lib/librte_pmd_ixgbe/ixgbe_rxtx.c:4072: error: (near initialization for ‘dev_info.driver_name’)
>
> lib/librte_pmd_ixgbe/ixgbe_rxtx.c: In function ‘ixgbe_recv_pkts_lro_single_alloc’:
> lib/librte_pmd_ixgbe/ixgbe_rxtx.c:1479: error: ‘next_rsc_entry’ may be used uninitialized in this function
> lib/librte_pmd_ixgbe/ixgbe_rxtx.c:1480: error: ‘next_rxe’ may be used uninitialized in this function
>
> The "missing initializer" warning is a GCC bug which seems fixed in 4.7.
> The "may be used uninitialized" warning seems to be another GCC bug and is
> workarounded with NULL initialization.
>
> Fixes: 8eecb3295aed ("ixgbe: add LRO support")
>
> Signed-off-by: Thomas Monjalon <thomas.monjalon-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>
> ---
> changes in v2:
> - option -Wno-missing-field-initializers for old GCC instead of code workaround
>
>   lib/librte_pmd_ixgbe/ixgbe_rxtx.c | 4 ++--
>   mk/toolchain/gcc/rte.vars.mk      | 5 +++++
>   2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> index f1da9ec..6475c44 100644
> --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> @@ -1476,8 +1476,8 @@ ixgbe_recv_pkts_lro(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts,
>   		bool eop;
>   		struct ixgbe_rx_entry *rxe;
>   		struct ixgbe_rsc_entry *rsc_entry;
> -		struct ixgbe_rsc_entry *next_rsc_entry;
> -		struct ixgbe_rx_entry *next_rxe;
> +		struct ixgbe_rsc_entry *next_rsc_entry = NULL;
> +		struct ixgbe_rx_entry *next_rxe = NULL;

-Wno-maybe-uninitialized ?

>   		struct rte_mbuf *first_seg;
>   		struct rte_mbuf *rxm;
>   		struct rte_mbuf *nmb;
> diff --git a/mk/toolchain/gcc/rte.vars.mk b/mk/toolchain/gcc/rte.vars.mk
> index 88f235c..208cddd 100644
> --- a/mk/toolchain/gcc/rte.vars.mk
> +++ b/mk/toolchain/gcc/rte.vars.mk
> @@ -80,5 +80,10 @@ WERROR_FLAGS += -Wundef -Wwrite-strings
>   # process cpu flags
>   include $(RTE_SDK)/mk/toolchain/$(RTE_TOOLCHAIN)/rte.toolchain-compat.mk
>   
> +# workaround GCC bug with warning "missing initializer" for "= {0}"
> +ifeq ($(shell test $(GCC_VERSION) -lt 47 && echo 1), 1)
> +WERROR_FLAGS += -Wno-missing-field-initializers
> +endif
> +
>   export CC AS AR LD OBJCOPY OBJDUMP STRIP READELF
>   export TOOLCHAIN_CFLAGS TOOLCHAIN_LDFLAGS TOOLCHAIN_ASFLAGS