Re: [PATCH 3/6] net: make NET a menuconfig (and downgrade NO_NET to a simple config)

[Heinrich Schuchardt]

Am 21. April 2026 10:37:54 MESZ schrieb Quentin Schulz <quentin.schulz at cherry.de>:
>Hi Heinrich,
>
>On 4/20/26 10:24 PM, Heinrich Schuchardt wrote:
>> Am 20. April 2026 13:36:09 MESZ schrieb Quentin Schulz <foss+uboot at 0leil.net>:
>>> From: Quentin Schulz <quentin.schulz at cherry.de>
>>> 
>>> 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 <quentin.schulz at cherry.de>
>>> ---
>>> 
>>> I'd say we should have everything net-related depends on NET as well,
>>> so that disabling networking support with NET=n is also disabling
>>> anything related (e.g. Ethernet controller and PHY drivers, USB
>>> Ethernet, USB gadget CDC/RNDIS, network CLI commands, etc.).
>>> ---
>>> configs/am62px_evm_r5_ethboot_defconfig |  2 +-
>>> configs/j722s_evm_r5_ethboot_defconfig  |  2 +-
>>> net/Kconfig                             | 23 ++++++++++++-----------
>>> 3 files changed, 14 insertions(+), 13 deletions(-)
>>> 
>>> diff --git a/configs/am62px_evm_r5_ethboot_defconfig b/configs/am62px_evm_r5_ethboot_defconfig
>>> index 8baec9d43ff..df49324b25a 100644
>>> --- a/configs/am62px_evm_r5_ethboot_defconfig
>>> +++ b/configs/am62px_evm_r5_ethboot_defconfig
>>> @@ -5,7 +5,7 @@ CONFIG_ARCH_K3=y
>>> CONFIG_SOC_K3_AM62P5=y
>>> CONFIG_TARGET_AM62P5_R5_EVM=y
>>> CONFIG_DEFAULT_DEVICE_TREE="k3-am62p5-r5-sk"
>>> -CONFIG_NET_LEGACY=y
>>> +# CONFIG_NO_NET is not set
>> 
>> Does this imply that NET_LEGACY is the default? Choosing LEGACY as default would not be plausible to me. We should use LWIP as default. Then every new board will use it, hopefully.
>> 
>
>(below, "current" means the value in master branch, so before this series is applied).
>
>(current) CONFIG_NET is the default already, see https://source.denx.de/u-boot/u-boot/-/blob/master/Kconfig#L794-L824. This series does not aim to change anything but the name of the symbols. Yes, we could make NET_LWIP the new default stack, but not in this series. Also, we have an issue that if you enable SPL_NET you need the legacy stack, even in proper (according to https://source.denx.de/u-boot/u-boot/-/blob/master/common/spl/Kconfig#L1152-L1154). So we would need to tackle this first (we don't necessarily need to support lwIP in SPL, just that the choice in SPL shouldn't impact the choice in proper).
>
>If you're asking about this defconfig specifically, it's simply because it is not a typical defconfig. It includes configs/am62px_evm_r5_defconfig which sets CONFIG_NO_NET=y. Because NO_NET used to (before this series) be a choice with (current) NET and NET_LWIP, am62px_evm_r5_ethboot_defconfig needed to override it with another choice, namely (current) NET. Because NET_LEGACY is automatically selected when NO_NET is unset (due to NET default y), we only need to unset NO_NET in configs/am62px_evm_r5_ethboot_defconfig to restore the current state of enabling the legacy stack (current NET, now NET_LEGACY). This is not changing anything, just moving things around.
>
>Does this answer your question?
>
>Cheers,
>Quentin


Acked-by: Heinrich Schuchardt <xypron.glpk at gmx.de>