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

[Jerin Jacob Kollanukkaran <jerinj@marvell.com>]

On Wed, 2019-01-23 at 16:24 +0000, Honnappa Nagarahalli wrote:
> > > > > > > I'll come up with a new patch based on the discussion
> > > > > > > here.
> > > > > > > A few things noted,
> > > > > > > - we still want it to be 128B for generic build
> > > > > > > - we at least agreed on changing it to 64B for A72
> > > > > > How will this be done? Will you add
> > > > > > config/arm/arm64_bluefield_linuxapp_gcc?
> > > > > I asked this question as there was a proposal containing
> > > > > 'a72' in
> > > > > the file name. IMO, the file name should contain 'bluefield',
> > > > > not
> > > > > on a72.
> > > > 
> > > > Sorry for late reply. It's been buried for some reason. :-)
> > > No problem
> > > 
> > > > Nope, I won't create such a file. That's for cross-compiler
> > > > AFAIK.
> > > > I'm thinking about changing meson.build. Currently, one CL size
> > > > is
> > > > applied to all kinds of cores. Consequently, for armv8a, both
> > > > 'default' and 'a72' have to have the same CL size. And one more
> > > > thing raised from ARM was that 'crypto' in -march can't be a
> > > > default.
> > > Yes, crypto is optional. So, the distro builds (and any other
> > > builds
> > > for binary compatibility) should not expect crypto to be present
> > > by
> > > default.
> > 
> > IMO, crypto case is different where DPDK code check at runtime to
> > see crypto
> > instruction present in the given CPU before it uses any crypto
> > instructions. so
> > IMO, There is no harm in building with crypto enabled unlike other
> > gcc flags.
> > 
> Right now, DPDK does not boot on a platform with crypto disabled. Do
> you suggest we remove the run time check in DPDK?

May be we need to introduce a framework to define mandatory cpu flags
and optional flags. Check only mandatory flags at bootup or some
abstraction where we can express above scenario like cryto flag case.



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