Niklo
Posts: 4
Joined: Wed Feb 28, 2018 12:53 pm

Problem with sound running a 64Bit kernel

Thu Mar 08, 2018 9:31 pm

Hi,
I have problems to use sound running my new compiled 64 Bit kernel. The kernel module snd_bcm2835 is not compiled and I don't know how to do config the kernel to do it.
I used the following description to build the 64 Bit linux kernel:
http://www.tal.org/tutorials/raspberry- ... bit-kernel

At first I build binutils-2.29.1 (binutils 2.30 caused linker problems during the kernel build). Afterwards I build a gcc 6.4.0 as cross compiler to build 64 Bit binaries on my Raspberry Pi 3B on Raspbian stretch. For building the latest 4.9 kernel I fetched the kernel sources with git. Now comes the most interesting part. The kernel configuration:

make O=../kernel-out/ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bcmrpi3_defconfig

The same is written in
https://devsidestory.com/build-a-64-bit ... erry-pi-3/

The build finishes without problems but the sound modules are missing. I can start Raspbian with the new kernel. Wifi works, wireless keyboard, too and X11....

I looked for the snd_bcm2835.ko The old 32Bit kernel had it in
/lib/modules/4.9.59-v7+/kernel/sound/arm/snd-bcm2835.ko
The new 64 Bit has no such module in
/lib/modules/4.9.80-v8+/kernel/sound
I found
/lib/modules/4.9.80-v8+/kernel/sound/soc/bcm/snd-soc-bcm2835-i2s.ko
but I guess it's something different. This module exists for 32 Bit, too.
[email protected]:/lib/modules/4.9.59-v7+/kernel/sound $ find . -name \*bcm\*.ko
./arm/snd-bcm2835.ko
./soc/bcm/snd-soc-bcm2835-i2s.ko

Has anybody an idea how build kernel/sound/arm/snd-bcm2835.ko or how to get sound working after compiling a 64 Bit kernel?


By the way that is the output of uname and lsmod:
uname -a
Linux raspberrypi 4.9.80-v8+ #1 SMP PREEMPT Tue Mar 6 09:14:24 CET 2018 aarch64 GNU/Linux

Loaded kernel module :
[email protected]:~ $ lsmod | sort
bluetooth 397312 29 hci_uart,bnep,btbcm,rfcomm
bnep 24576 2
brcmfmac 262144 0
brcmutil 20480 1 brcmfmac
btbcm 16384 1 hci_uart
cfg80211 667648 1 brcmfmac
cmac 16384 1
evdev 24576 1
hci_uart 32768 1
hid_logitech_dj 24576 0
hid_logitech_hidpp 32768 0
i2c_dev 20480 0
ip_tables 32768 0
ipv6 458752 24
joydev 20480 0
Module Size Used by
rfcomm 53248 6
rfkill 36864 6 bluetooth,cfg80211
uio 24576 1 uio_pdrv_genirq
uio_pdrv_genirq 16384 0
x_tables 45056 1 ip_tables

It would be great if you could help me.
Best regards,
Roland

Niklo
Posts: 4
Joined: Wed Feb 28, 2018 12:53 pm

Re: Problem with sound running a 64Bit kernel

Sat Mar 10, 2018 11:54 am

Hi,
I recently got sound working. I found some differences between:
bcm2709_defconfig and bcmrpi3_defconfig. Especially
CONFIG_SND_BCM2835=m
was missing in bcmrpi3_defconfig
So that was the reason for starting a thread in
I started a thread on
https://github.com/raspberrypi/linux/issues/2430
too. The answer is not very helpful but at least I got an answer.
64 Bit is not well supported because of VC4.
I did not give up and fetched the 4.10 kernel
git clone --depth=1 -b rpi-4.10.y https://github.com/raspberrypi/linux.git
and this helped and build the sound kernel module. Now I can use sound on 64 Bit in Raspbian on my Raspberry 3.
I hope this information helps other people.
Best regards,
Roland

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