[dpdk-dev] [PATCH 1/3] mk: fix librte_pipeline dependency list truncation

[Dumitrescu, Cristian]

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Panu Matilainen
> Sent: Tuesday, June 21, 2016 9:12 AM
> To: dev at dpdk.org
> Cc: christian.ehrhardt at canonical.com; thomas.monjalon at 6wind.com
> Subject: [dpdk-dev] [PATCH 1/3] mk: fix librte_pipeline dependency list
> truncation
> 
> In other libraries, dependency list is always appended to, but
> in commit 6cbf4f75e059 it with an assignment. This causes the
> librte_eal dependency added in commit 6cbf4f75e059 to get discarded,
> resulting in missing dependency on librte_eal.
> 
> Fixes: b3688bee81a8 ("pipeline: new packet framework logic")
> Fixes: 6cbf4f75e059 ("mk: fix missing internal dependencies")
> 
> Signed-off-by: Panu Matilainen <pmatilai at redhat.com>
> ---
>  lib/librte_pipeline/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/librte_pipeline/Makefile b/lib/librte_pipeline/Makefile
> index 95387aa..a8f3128 100644
> --- a/lib/librte_pipeline/Makefile
> +++ b/lib/librte_pipeline/Makefile
> @@ -53,7 +53,7 @@ SYMLINK-$(CONFIG_RTE_LIBRTE_PIPELINE)-include +=
> rte_pipeline.h
> 
>  # this lib depends upon:
>  DEPDIRS-$(CONFIG_RTE_LIBRTE_PIPELINE) += lib/librte_eal
> -DEPDIRS-$(CONFIG_RTE_LIBRTE_PIPELINE) := lib/librte_table
> +DEPDIRS-$(CONFIG_RTE_LIBRTE_PIPELINE) += lib/librte_table
>  DEPDIRS-$(CONFIG_RTE_LIBRTE_PIPELINE) += lib/librte_port
> 
>  include $(RTE_SDK)/mk/rte.lib.mk
> --
> 2.5.5


In release 16.4, EAL was missing from the dependency list, now it is added. The librte_pipeline uses rte_malloc, therefore it depends on librte_eal being present.

In the Makefile of the other Packet Framework libraries (librte_port, librte_table), it looks like the first dependency in the list is EAL, which is listed with the assignment operator, followed by others that are listed with the append operator:
	DEPDIRS-$(CONFIG_RTE_LIBRTE_XYZ) := lib/librte_eal
	DEPDIRS-$(CONFIG_RTE_LIBRTE_XYZ) += lib/librte_some other lib

Therefore, at least for cosmetic reasons, we should probably do the same in librte_pipeline, which requires changing both the librte_eal and the librte_table lines as below:
	DEPDIRS-$(CONFIG_RTE_LIBRTE_PIPELINE) := lib/librte_eal
	DEPDIRS-$(CONFIG_RTE_LIBRTE_PIPELINE) += lib/librte_table
	DEPDIRS-$(CONFIG_RTE_LIBRTE_PIPELINE) += lib/librte_port

However, some other libraries e.g. librte_lpm simply add the EAL dependency using the append operator:
	DEPDIRS-$(CONFIG_RTE_LIBRTE_LPM) += lib/librte_eal

To be honest, I need to refresh my knowledge on make, I don't remember right now when we should use the assignment and when the append. Do we need to use the assign for first dependency (EAL) and append for others or should we use append everywhere?

Thanks,
Cristian