[dpdk-dev] [PATCH v2 01/10] Add __rte_internal tag for functions and version target

[Wang, Haiyue]

Hi Neil,

> -----Original Message-----
> From: dev <dev-bounces at dpdk.org> On Behalf Of Neil Horman
> Sent: Thursday, June 13, 2019 22:24
> To: dev at dpdk.org
> Cc: Neil Horman <nhorman at tuxdriver.com>; Jerin Jacob Kollanukkaran <jerinj at marvell.com>; Richardson,
> Bruce <bruce.richardson at intel.com>; Thomas Monjalon <thomas at monjalon.net>
> Subject: [dpdk-dev] [PATCH v2 01/10] Add __rte_internal tag for functions and version target
> 
> This tag is meant to be used on function prototypes to identify
> functions that are only meant to be used by internal DPDK libraries
> (i.e. libraries that are built while building the SDK itself, as
> identified by the defining of the BUILDING_RTE_SDK macro).  When that
> flag is not set, it will resolve to an error function attribute, causing
> build breakage for any compilation unit attempting to build it
> 
> Validate the use of this tag in much the same way we validate
> __rte_experimental.  By adding an INTERNAL version to library map files,
> we can exempt internal-only functions from ABI checking, and handle them
> to ensure that symbols we wish to only be for internal use between dpdk
> libraries are properly tagged with __rte_experimental
> 
> Note this patch updates the check-experimental-syms.sh script, which
> normally only check the EXPERIMENTAL section to also check the INTERNAL
> section now.  As such its been renamed to the now more appropriate
> check-special-syms.sh
> 
> Signed-off-by: Neil Horman <nhorman at tuxdriver.com>
> CC: Jerin Jacob Kollanukkaran <jerinj at marvell.com>
> CC: Bruce Richardson <bruce.richardson at intel.com>
> CC: Thomas Monjalon <thomas at monjalon.net>
> ---
>  ...rimental-syms.sh => check-special-syms.sh} | 24 ++++++++++++++++++-
>  lib/librte_eal/common/include/rte_compat.h    | 12 ++++++++++
>  mk/internal/rte.compile-pre.mk                |  6 ++---
>  mk/target/generic/rte.vars.mk                 |  2 +-
>  4 files changed, 39 insertions(+), 5 deletions(-)
>  rename buildtools/{check-experimental-syms.sh => check-special-syms.sh} (53%)
> 
....

> diff --git a/lib/librte_eal/common/include/rte_compat.h b/lib/librte_eal/common/include/rte_compat.h
> index 92ff28faf..739e8485c 100644
> --- a/lib/librte_eal/common/include/rte_compat.h
> +++ b/lib/librte_eal/common/include/rte_compat.h
> @@ -89,4 +89,16 @@ __attribute__((section(".text.experimental")))
> 
>  #endif
> 
> +/*
> + * __rte_internal tags mark functions as internal only, If specified in public
> + * header files, this tag will resolve to an error directive, preventing
> + * external applications from attempting to make calls to functions not meant
> + * for consumption outside the dpdk library
> + */
> +#ifdef BUILDING_RTE_SDK
> +#define __rte_internal __attribute__((section(".text.internal")))
> +#else
> +#define __rte_internal __attribute__((error("This function cannot be used outside of the core DPDK
> library"), \
> +	section(".text.internal")))
> +#endif
>  #endif /* _RTE_COMPAT_H_ */

Since struct definition is also a kind of ABI (am I right ? ;-) ), like:

drivers/bus/pci/rte_bus_pci.h
struct rte_pci_device {
	...
	struct rte_intr_handle vfio_req_intr_handle;
				/**< Handler of VFIO request interrupt */
} __rte_internal;

Then will capture the errors anyway by using one of __rte_internal definition.
	error: 'section' attribute does not apply to types [-Werror=attributes]
	error: 'error' attribute does not apply to types

> 2.20.1