Re: [PATCH v2 1/5] build: add meson option to configure IOVA mode as VA

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Sep 07, 2022 at 08:31:09AM -0700, Stephen Hemminger wrote:
> On Wed, 7 Sep 2022 19:13:36 +0530 Shijith Thotton <sthotton@marvell.com>
> wrote:
> 
> > IOVA mode in DPDK is either PA or VA. The new build option iova_as_va
> > configures the mode to VA at compile time and prevents setting it to PA
> > at runtime. For now, all drivers which are not always enabled are
> > disabled with this option. Supported driver can set the flag
> > pmd_iova_as_va in its build file to enable build.
> > 
> > mbuf structure holds the physical (PA) and virtual address (VA) of a
> > buffer. if IOVA mode is set to VA, PA is redundant as it is the same as
> > VA. So PA field need not be updated and marked invalid if the build is
> > configured to use only VA.
> > 
> > Signed-off-by: Shijith Thotton <sthotton@marvell.com>
> 
> NAK This works ok for use cases where NFV is building local version of
> DPDK, but meson options dont work for distro vendors.
> 
I think for something of this magnitude a build-time option is definitely
the way to go. Sure, it won't be available in distro-packages, but for
something like this it's just too invasive - and rather niche IMHO - to
make a runtime option.

/Bruce