net: make NET a menuconfig (and downgrade NO_NET to a simple config)

This will allow a bunch of simplifications across the code base.
Disabling NET is the equivalent of today's NO_NET choice. This means
that if NET is enabled, either the legacy or lwIP stack is necessarily
selected, which allows us to simplify if NET_LEGACY || NET_LWIP into
if NET in a later commit.

Config fragments - or defconfigs including other defconfigs - setting
the network stack (NET_LEGACY or NET_LWIP) must also set NET (or unset
NO_NET) if the config they apply to - or the included defconfigs -
unsets NET (or selects NO_NET) as otherwise the NET_LEGACY and NET_LWIP
symbols are unreachable. This is the case for the two defconfig modified
in this commit.

NO_NET is now a convenience symbol which hides NET entirely to avoid
modifying many defconfigs. If one selected NO_NET to disable the
networking stack in the past, this will still work for now. Technically,
we should be using the "transitional" Kconfig attribute but that is only
available since Kconfig from Linux kernel v6.18 and we're on 6.1 right
now.

Note that this moves CONFIG_SYS_RX_ETH_BUFFER from under the Network
menu back into the main menu as it seems like it needs to be defined
even when there's no need for NET support at all and menuconfig option
doesn't work the same way as a menu.

Signed-off-by: Quentin Schulz <[email protected]>
Reviewed-by: Simon Glass <[email protected]>
Acked-by: Heinrich Schuchardt <[email protected]>
Reviewed-by: Peter Robinson <[email protected]>
Reviewed-by: Tom Rini <[email protected]>

0 files changed, 0 insertions, 0 deletions