[dpdk-dev] [EXT] Default cacheline size for ARM

[Honnappa Nagarahalli]

> > > > > > > Hi,
> > > > > > >
> > > > > > > The cacheline size (RTE_CACHE_LINE_SIZE) for ARM CPUs is set
> > > > > > > to be 128B by default. Mellanox's BlueField is an ARM CPU
> > > > > > > having
> > > > > > > Cortex-A72
> > > > > > > and its CL size is 64B.
> > > > > Just wondering how many devices are out there with 128B cache
> > > > > line? I also have not heard about any future devices with 128B
> > > > > cache line. If the majority is 64B, why not keep 64B as the
> > > > > default?
> > > >
> > > > The problem is, In the armv8 spec the cache line size is
> > > > IMPLEMENTATION DEFINED. Marvell's embedded processors has 128B
> CL
> > > > and Server processors has 64B CL.
> > > >
> > > > Assuming the defconfig_arm64-armv8a-linuxapp-gcc will be used by
> > > > distro folks then that configuration should support all the
> > > > devices with
> > > > armv8.1 spec. For instance, marvells new chips are armv8.2 but we
> > > > can not make that as default.
> > > What will happen in the future when we will have v9, v10 etc? I
> > > think the distro(generic/binary portable) config should get rid of v8.
> >
> > Will it be too much overhead if the image is same for v8, v9 and v10.
> > I think, we can inline with what distro folks are doing for other
> > packages, I think, DPDK package does not need any exception.
> Yes, we need to be inline with any other package. My understanding is that
> the image will be same for v8,v9,v10 (any input from distro engineers will
> help here). So, my question is, should the config file/name used by distros
> contain anything specific to armv8?
Jerin, after following [1], I am not unable to understand when the file config/arm/arm64_armv8_linuxapp_gcc gets used. Is this file required?

1. http://mails.dpdk.org/archives/dev/2019-January/123272.html