[PATCH v2 1/2] build: clarify configuration without IOVA field in mbuf

[Morten Brørup]

> From: Thomas Monjalon [mailto:thomas at monjalon.net]
> Sent: Monday, 6 March 2023 17.13
> 
> The impact of the option "enable_iova_as_pa" is explained for users.
> 
> Also the code flag "RTE_IOVA_AS_PA" is renamed as "RTE_IOVA_IN_MBUF"
> in order to be more accurate (IOVA mode is decided at runtime),
> and more readable in the code.
> 
> Similarly the drivers are using the variable "require_iova_in_mbuf"
> instead of "pmd_supports_disable_iova_as_pa" with an opposite meaning.
> By default, it is assumed that drivers require the IOVA field in mbuf.
> The drivers which support removing this field have to declare
> themselves.
> 
> If the option "enable_iova_as_pa" is disabled, the unsupported drivers
> will be listed with the new reason text "requires IOVA in mbuf".
> 
> Suggested-by: Bruce Richardson <bruce.richardson at intel.com>
> Signed-off-by: Thomas Monjalon <thomas at monjalon.net>
> ---

Good clean-up.

Acked-by: Morten Brørup <mb at smartsharesystems.com>