Re: [Buildroot] [PATCH 3/5] configs/rock5b: enable eudev to enable automatic module loading

[Niklas Cassel via buildroot <buildroot@buildroot.org>]

On Tue, Sep 03, 2024 at 09:50:53PM +0200, Arnout Vandecappelle wrote:
> 
> 
> On 03/09/2024 21:26, Thomas Petazzoni via buildroot wrote:
> > On Mon,  2 Sep 2024 12:44:31 +0200
> > Niklas Cassel via buildroot <buildroot@buildroot.org> wrote:
> > 
> > > From: Niklas Cassel <cassel@kernel.org>
> > > 
> > > The arm64 defconfig enables both the R8169 Ethernet driver and the
> > > PHY_ROCKCHIP_NANENG_COMBO_PHY PHY driver as modules.
> > > 
> > > Enable udev so that these modules will get automatically loaded by udev
> > > after the rootfs is mounted from the SD card.
> > > 
> > > This way, we do not need to build these modules as built-in, and we also
> > > get the benefit that any device plugged in to the PCIe slot will get
> > > automatically loaded.
> > > 
> > > Signed-off-by: Niklas Cassel <cassel@kernel.org>
> > 
> > I'm not sure what we want to do here, especially when this ends up
> > needing net.ifnames=0 that you add in PATCH 4/5.
> > 
> > We do have already a small number of defconfigs that enable eudev. So
> > far we only use net.ifnames=0 in 4 configurations.
> > 
> > Basically, I'm trying to make sure we remain consistent and have a
> > policy that applies to all defconfigs rather than ad-hoc solutions that
> > are different for each and every defconfig. That's why I'm a bit
> > reluctant with applying your patches as-is because they only solve the
> > specific case of this defconfig, in a specific way, without creating a
> > clear rule that all defconfigs meeting a specific situation should
> > follow.
> 
>  We don't really have a policy or rules at the moment. I've added this to
> the topics of the Buildroot Developer meeting in Vienna.

See my reply to Thomas where I suggest to create a
BR2_PACKAGE_EUDEV_PREDICTABLE_NIC_NAMES Kconfig which is default not set.

I think that would be a nice policy / solution.


> 
>  For the time being, I think we generally prefer to have a kernel config
> that is as much as possible custom for the target board. Thus, we also
> generally prefer to not require loading modules. Certainly for ethernet -
> having ethernet as a module makes nfsroot impossible.
> 
>  So I've marked patches 3/5 and 4/5 as Rejected.
> 
>  Feel free to give arguments why we should prefer these drivers as module though!

Sure, we could keep the Ethernet driver as built-in.

I still think it is a really good idea to enable udev though.

rock5b is currently using arm64 defconfig as kernel config.


Just enabling udev shows this in lsmod:

# lsmod
Module                  Size  Used by    Not tainted
hantro_vpu            270336  0 
rockchipdrm           167936  0 
v4l2_jpeg              16384  1 hantro_vpu
v4l2_vp9               20480  1 hantro_vpu
v4l2_h264              12288  1 hantro_vpu
analogix_dp            36864  1 rockchipdrm
v4l2_mem2mem           36864  1 hantro_vpu
dw_mipi_dsi            20480  1 rockchipdrm
panthor               118784  0 
videobuf2_dma_contig    16384  1 hantro_vpu
dw_hdmi                40960  1 rockchipdrm
videobuf2_memops       12288  1 videobuf2_dma_contig
cec                    53248  1 dw_hdmi
drm_gpuvm              32768  1 panthor
videobuf2_v4l2         28672  2 hantro_vpu,v4l2_mem2mem
drm_exec               12288  2 panthor,drm_gpuvm
drm_display_helper    167936  3 rockchipdrm,analogix_dp,dw_hdmi
drm_shmem_helper       24576  1 panthor
drm_dma_helper         20480  1 rockchipdrm
crct10dif_ce           12288  1 
videodev              253952  3 hantro_vpu,v4l2_mem2mem,videobuf2_v4l2
rockchip_saradc        16384  0 
gpu_sched              40960  1 panthor
videobuf2_common       57344  5 hantro_vpu,v4l2_mem2mem,videobuf2_dma_contig,videobuf2_memops,videobuf2_v4l2
drm_kms_helper        188416  7 rockchipdrm,analogix_dp,dw_mipi_dsi,dw_hdmi,drm_display_helper,drm_shmem_helper,drm_dma_helper
mc                     57344  5 hantro_vpu,v4l2_mem2mem,videobuf2_v4l2,videodev,videobuf2_common
drm                   552960 12 rockchipdrm,analogix_dp,dw_mipi_dsi,panthor,dw_hdmi,drm_gpuvm,drm_exec,drm_display_helper,drm_shmem_helper,drm_dma_helper,gpu_sched,drm_kms_helper
industrialio_triggered_buffer    12288  1 rockchip_saradc
backlight              20480  2 drm_display_helper,drm
phy_rockchip_usbdp     20480  2 
phy_rockchip_naneng_combphy    16384  5 
kfifo_buf              12288  1 industrialio_triggered_buffer
pwm_fan                16384  0 
rtc_hym8563            12288  1 
snd_soc_audio_graph_card    16384  0 
typec                  77824  1 phy_rockchip_usbdp
snd_soc_rockchip_i2s_tdm    20480  2 
snd_soc_simple_card_utils    28672  1 snd_soc_audio_graph_card
snd_soc_es8316         40960  1 
rockchip_thermal       24576  0 
spi_rockchip_sfc       12288  0 
rk805_pwrkey           12288  0 

Without udev (i.e. with the current buildroot rock5b_defconfig)
none of these modules will be loaded.


Kind regards,
Niklas
_______________________________________________
buildroot mailing list
buildroot@buildroot.org
https://lists.buildroot.org/mailman/listinfo/buildroot