Re: [PATCH] drivers: skip build of sub-libs not supporting IOVA mode

[Thomas Monjalon <thomas@monjalon.net>]

02/03/2023 15:16, Zhang, Qi Z:
> From: Thomas Monjalon <thomas@monjalon.net>
> > 02/03/2023 14:52, Zhang, Qi Z:
> > > From: Thomas Monjalon <thomas@monjalon.net>
> > > > If IOVA as PA is disabled and the driver does not support IOVA as
> > > > VA, the build of the driver was disabled.
> > > > Unfortunately some drivers were building some sub-libraries (with
> > > > specific options for vector paths) which were not disabled.
> > > >
> > > > The build parsing of those drivers need to be skipped earlier to
> > > > avoid defining the sub-libraries.
> > > >
> > > > Fixes: a986c2b7973d ("build: add option to configure IOVA mode as
> > > > PA")
> > > > Cc: stable@dpdk.org
> > > >
> > > > Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> > [...]
> > > > --- a/drivers/meson.build
> > > > +++ b/drivers/meson.build
> > > > @@ -127,9 +127,9 @@ foreach subpath:subdirs
> > > >              # pull in driver directory which should update all the local
> > variables
> > > >              subdir(drv_path)
> > > >
> > > > -            if dpdk_conf.get('RTE_IOVA_AS_PA') == 0 and not
> > > > pmd_supports_disable_iova_as_pa and not
> > > > always_enable.contains(drv_path)
> > > > +            if not get_option('enable_iova_as_pa') and not
> > > > + pmd_supports_disable_iova_as_pa and not
> > > > + always_enable.contains(drv_path)
> > > >                  build = false
> > > > -                reason = 'driver does not support disabling IOVA as PA mode'
> > > > +                reason = 'IOVA as VA not supported'
> > > >              endif
> > >
> > > If we check enable_iova_as_pa for each unsupported driver , do we still
> > need "pmd_supports_disable_iova_as_pa"?
> > 
> > They are a bit redundant.
> 
> That's why I prefer my previous solution for i40e and iavf,
> because, someday we may claim pmd_supports_disable_iova_as_pa = true but still leave avx part not be fixed.

Both are in the same file, so I don't see how it could be missed,
especially if those lines are placed together.

We have a variable used commonly with a standardized message, we must use it,
at least to allow easy grep of this support.

> > The idea is to use pmd_supports_disable_iova_as_pa (could be renamed) as
> > it is simpler to use.
> > But in the case of drivers having sub-libs (always enabled), we need an extra
> > check of enable_iova_as_pa inside the driver file.