Re: [EXT] [PATCH] config: change default cache line size for ARMv8 with meson

[Yongseok Koh <yskoh@mellanox.com>]

> On Jan 9, 2019, at 2:09 AM, Jerin Jacob Kollanukkaran <jerinj@marvell.com> wrote:
> 
> On Wed, 2019-01-09 at 01:39 -0800, Yongseok Koh wrote:
>> 
>> -------------------------------------------------------------------
>> ---
>> In config/arm64_armv8_linuxapp_gcc, maximum available cache line size
>> (128B) in arm64 implementations is set by default for generic config.
>> However, setting 64B is preferable for meson build in order to
>> support
>> majority of CPUs which don't have Implementor ID or Part Number
>> programmed
>> on chip.
> 
> Adding Luca to get input from distro build perspective.
> 
> If I understand it correctly, distro build will be using
> the generic config/arm/arm64_armv8_linuxapp_gcc for generic build.
> If so, We can not change cache line size for generic config
> as mentined the reason are
> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmails.dpdk.org%2Farchives%2Fdev%2F2019-January%2F122441.html&amp;data=02%7C01%7Cyskoh%40mellanox.com%7Cf0818214ecbf492d5c1408d6761a9136%7Ca652971c7d2e4d9ba6a4d149256f461b%7C0%7C0%7C636826253828868015&amp;sdata=7pT%2BPTNslOpTCIqFjaZ223Hg3btpDB3dGC9xiy13wDA%3D&amp;reserved=0

My understanding from your comment was distro build doesn't use meson
but make with config/defconfig_arm64-armv8a-linuxapp-gcc.
Let's hear from Luca.

> I think, I way forward is to add config/arm/arm64_a72_linuxapp_gcc
> for meson. This config can be used for all SoC with A72 armv8 
> implementation and may have sym link to specfific SoC to avoid
> confusion to end users.

Is config/arm/arm64_a72_linuxapp_gcc valid? Others have arm64_[IMPLEMENTOR]_linuxapp_gcc.
a72 is got from PartNum.

Thanks,
Yongseok

>> 
>> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
>> ---
>> 
>> Discussion on the mailing list:
>>    https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmails.dpdk.org%2Farchives%2Fdev%2F2019-January%2F122441.html&amp;data=02%7C01%7Cyskoh%40mellanox.com%7Cf0818214ecbf492d5c1408d6761a9136%7Ca652971c7d2e4d9ba6a4d149256f461b%7C0%7C0%7C636826253828868015&amp;sdata=7pT%2BPTNslOpTCIqFjaZ223Hg3btpDB3dGC9xiy13wDA%3D&amp;reserved=0
>> 
>> config/arm/meson.build | 11 +++++++----
>> 1 file changed, 7 insertions(+), 4 deletions(-)
>> 
>> diff --git a/config/arm/meson.build b/config/arm/meson.build
>> index dae55d6b26..3af256a5ec 100644
>> --- a/config/arm/meson.build
>> +++ b/config/arm/meson.build
>> @@ -47,8 +47,7 @@ flags_common_default = [
>> flags_generic = [
>> 	['RTE_MACHINE', '"armv8a"'],
>> 	['RTE_MAX_LCORE', 256],
>> -	['RTE_USE_C11_MEM_MODEL', true],
>> -	['RTE_CACHE_LINE_SIZE', 128]]
>> +	['RTE_USE_C11_MEM_MODEL', true]]
>> flags_cavium = [
>> 	['RTE_MACHINE', '"thunderx"'],
>> 	['RTE_CACHE_LINE_SIZE', 128],
>> @@ -89,15 +88,19 @@ impl_dpaa2 = ['NXP DPAA2', flags_dpaa2,
>> machine_args_generic]
>> 
>> dpdk_conf.set('RTE_FORCE_INTRINSICS', 1)
>> 
>> +# In config/arm64_armv8_linuxapp_gcc, maximum available cache line
>> size (128B)
>> +# in arm64 implementations is set by default for generic config.
>> However,
>> +# setting 64B is preferable for meson build in order to support
>> majority of CPUs
>> +# which don't have Implementor ID or Part Number programmed on chip.
>> +dpdk_conf.set('RTE_CACHE_LINE_SIZE', 64)
>> +
>> if cc.sizeof('void *') != 8
>> -	dpdk_conf.set('RTE_CACHE_LINE_SIZE', 64)
>> 	dpdk_conf.set('RTE_ARCH_ARM', 1)
>> 	dpdk_conf.set('RTE_ARCH_ARMv7', 1)
>> 	# the minimum architecture supported, armv7-a, needs the
>> following,
>> 	# mk/machine/armv7a/rte.vars.mk sets it too
>> 	machine_args += '-mfpu=neon'
>> else
>> -	dpdk_conf.set('RTE_CACHE_LINE_SIZE', 128)
>> 	dpdk_conf.set('RTE_ARCH_ARM64', 1)
>> 	dpdk_conf.set('RTE_ARCH_64', 1)
>>