[PATCH 6/6] arm64: defconfig: Switch Ethernet drivers to modules

[Linus Walleij]

On Sun, Apr 12, 2026 at 6:21 PM Krzysztof Kozlowski
<krzysztof.kozlowski at oss.qualcomm.com> wrote:

> Development of Linux kernel progressed over last 10 years and it is easy
> to generate now initramfs for building own kernel, e.g. with Yocto or
> mkosi.  Therefore for a few years of reviews on mailing lists, all new
> options enabled in arm64 defconfig were with assumption of having
> initramfs which can load bare minimum of modules to mount filesystem
> from network or disk.  Basically network driver as built-in is not
> anymore essential to boot the system, so switch almost all Ethernet
> drivers to modules to save on kernel image size.
>
> Similarly 9P network filesystem for QEMU, especially that testing kernel
> unuder QEMU does not have any size or build process constraints and can
> use initramfs with -initrd argument.
>
> Notable exceptions / diff explanations:
>
> 1. Intel CONFIG_IGB stays as built-in, because of dependency on I2C
>    which is also built-in.
>
> 2. CONFIG_BCM4908_ENET and CONFIG_BCMASP appear in the diff, because
>    they were default=y (via ARCH_BCMBCA or ARCH_BCM_IPROC).
>
> 3. CONFIG_HNS3_HCLGE and CONFIG_HNS3_ENET are removed, because they are
>    default=m.
>
> Moving code to modules has positive impact on kernel image size, thus
> boot time of all users not using above drivers and ability to flash
> fixed-size boot partitions.
>
> Old Image size: 41.11 MiB (Image.gz: 14.69 MiB)
> New Image size: 39.14 MiB (Image.gz: 13.82 MiB)
>
> bloat-o-meter of vmlinux:
> add/remove: 4/6139 grow/shrink: 3/51 up/down: 34547/-2046619 (-2012072)
>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski at oss.qualcomm.com>

In principle I think this is a sound change.

But looping in netdev and Rafal to touch  base on how this might affect
deployed systems. We've had issues with ethernet drivers that don't
really like deferred probe for example.

Yours,
Linus Walleij