Re: [dpdk-dev] [RFC] hash: unify crc32 API header for x86 and ARM

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> >> From: Pavan Nikhilesh <pbhagavatula@marvell.com>
> >>
> >> Merge crc32 hash calculation public API headers for x86 and ARM,
> >> split implementations of x86 and ARM into their respective private
> >> headers.
> >> This reduces the ifdef code clutter while keeping current ABI intact.
> >>
> >> Although we install `rte_crc_arm64.h` it is not used in any of the lib or
> >> drivers layers. All the libs and drivers use `rte_hash_crc.h` which falls
> >> back to SW crc32 calculation for ARM platform.
> >>
> >> Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
> >> ---
> >>
> >>  Currently, if application incorrectly sets CRC32_ARM64 as crc32
> >algorithm
> >>  through `rte_hash_crc_set_alg()` on x86 or vice-versa we fallback to
> >algorithm
> >>  set previously via `rte_hash_crc_set_alg()` instead of setting the best
> >>  available.
> >>  This behaviour should probably change to setting the best available
> >algorithm
> >>  and is up for discussion.
> >>
> >>  app/test/test_hash.c            |   6 +
> >>  lib/librte_hash/Makefile        |   5 -
> >>  lib/librte_hash/crc_arm64.h     |  67 +++++++++++
> >>  lib/librte_hash/crc_x86.h       |  68 +++++++++++
> >>  lib/librte_hash/meson.build     |   3 +-
> >>  lib/librte_hash/rte_crc_arm64.h | 183 ------------------------------
> >>  lib/librte_hash/rte_hash_crc.h  | 193 +++++++++++++------------------
> >-
> >>  7 files changed, 219 insertions(+), 306 deletions(-)
> >>  create mode 100644 lib/librte_hash/crc_arm64.h
> >>  create mode 100644 lib/librte_hash/crc_x86.h
> >>  delete mode 100644 lib/librte_hash/rte_crc_arm64.h
> >>
> >> diff --git a/app/test/test_hash.c b/app/test/test_hash.c
> >> index afa3a1a3c..7bd457dac 100644
> >> --- a/app/test/test_hash.c
> >> +++ b/app/test/test_hash.c
> >> @@ -195,7 +195,13 @@ test_crc32_hash_alg_equiv(void)
> >>  	}
> >>
> >>  	/* Resetting to best available algorithm */
> >> +#if defined RTE_ARCH_X86
> >>  	rte_hash_crc_set_alg(CRC32_SSE42_x64);
> >> +#elif defined RTE_ARCH_ARM64
> >> +	rte_hash_crc_set_alg(CRC32_ARM64);
> >> +#else
> >> +	rte_hash_crc_set_alg(CRC32_SW);
> >> +#endif
> >>
> >>  	if (i == CRC32_ITERATIONS)
> >>  		return 0;
> >> diff --git a/lib/librte_hash/Makefile b/lib/librte_hash/Makefile
> >> index ec9f86499..f640afc42 100644
> >> --- a/lib/librte_hash/Makefile
> >> +++ b/lib/librte_hash/Makefile
> >> @@ -19,11 +19,6 @@ SRCS-$(CONFIG_RTE_LIBRTE_HASH) +=
> >rte_fbk_hash.c
> >>  # install this header file
> >>  SYMLINK-$(CONFIG_RTE_LIBRTE_HASH)-include := rte_hash.h
> >>  SYMLINK-$(CONFIG_RTE_LIBRTE_HASH)-include += rte_hash_crc.h
> >> -ifeq ($(CONFIG_RTE_ARCH_ARM64),y)
> >> -ifneq ($(findstring RTE_MACHINE_CPUFLAG_CRC32,$(CFLAGS)),)
> >> -SYMLINK-$(CONFIG_RTE_LIBRTE_HASH)-include += rte_crc_arm64.h
> >> -endif
> >> -endif
> >>  SYMLINK-$(CONFIG_RTE_LIBRTE_HASH)-include += rte_jhash.h
> >>  SYMLINK-$(CONFIG_RTE_LIBRTE_HASH)-include += rte_thash.h
> >>  SYMLINK-$(CONFIG_RTE_LIBRTE_HASH)-include += rte_fbk_hash.h
> >> diff --git a/lib/librte_hash/crc_arm64.h b/lib/librte_hash/crc_arm64.h
> >> new file mode 100644
> >> index 000000000..8e75f8297
> >
> >Wouldn't that break 'make  install T=...'?
> 
> My bad I verified with meson and it was building fine.
> 
> >As now rte_hash_crc.h includes not public headers (crc_x86.h, etc.).
> >Same question about external apps, where they would get from these
> >headers?
> 
> I think in the next version we can directly have the arch specific functions
> Implemented in rte_hash_crc.h. Since its pretty stable code and overhead of extra
> ~120 lines.

Ok... but why not then just leave arch specific headers, as they are right now?
What is wrong with current approach?