Kernel module does not compile on 6.6

[timothyb89]

Attempting to build the kernel module fails on a fresh install of Raspberry Pi OS (bookworm) running the 6.6.20 kernel on a Pi 4:

pi@piradio5:~/nrc7292_sw_pkg/package/src/nrc $ uname -a
Linux piradio5 6.6.20+rpt-rpi-v8 #1 SMP PREEMPT Debian 1:6.6.20-1+rpt1 (2024-03-07) aarch64 GNU/Linux
pi@piradio5:~/nrc7292_sw_pkg/package/src/nrc $ make

make[1]: Entering directory '/usr/src/linux-headers-6.6.20+rpt-rpi-v8'
  CC [M]  /home/pi/nrc7292_sw_pkg/package/src/nrc/nrc-netlink.o
/home/pi/nrc7292_sw_pkg/package/src/nrc/nrc-netlink.c:129:27: error: initialization of ‘int (*)(const struct genl_split_ops *, struct sk_buff *, struct genl_info *)’ from incompatible pointer type ‘int (*)(const struct genl_ops *, struct sk_buff *, struct genl_info *)’ [-Werror=incompatible-pointer-types]
  129 |         .pre_doit       = nrc_nl_pre_doit,
      |                           ^~~~~~~~~~~~~~~
/home/pi/nrc7292_sw_pkg/package/src/nrc/nrc-netlink.c:129:27: note: (near initialization for ‘nrc_nl_fam.pre_doit’)
/home/pi/nrc7292_sw_pkg/package/src/nrc/nrc-netlink.c:130:27: error: initialization of ‘void (*)(const struct genl_split_ops *, struct sk_buff *, struct genl_info *)’ from incompatible pointer type ‘void (*)(const struct genl_ops *, struct sk_buff *, struct genl_info *)’ [-Werror=incompatible-pointer-types]
  130 |         .post_doit      = nrc_nl_post_doit,
      |                           ^~~~~~~~~~~~~~~~
/home/pi/nrc7292_sw_pkg/package/src/nrc/nrc-netlink.c:130:27: note: (near initialization for ‘nrc_nl_fam.post_doit’)
cc1: all warnings being treated as errors
make[3]: *** [/usr/src/linux-headers-6.6.20+rpt-common-rpi/scripts/Makefile.build:248: /home/pi/nrc7292_sw_pkg/package/src/nrc/nrc-netlink.o] Error 1
make[2]: *** [/usr/src/linux-headers-6.6.20+rpt-common-rpi/Makefile:1938: /home/pi/nrc7292_sw_pkg/package/src/nrc] Error 2
make[1]: *** [/usr/src/linux-headers-6.6.20+rpt-common-rpi/Makefile:246: __sub-make] Error 2
make[1]: Leaving directory '/usr/src/linux-headers-6.6.20+rpt-rpi-v8'
make: *** [Makefile:50: modules] Error 2

[EugeneN]

It is a warning being treated as an error (see cc1: all warnings being treated as errors in the compiler output).

This warning can be disabled by adding -Wno-incompatible-pointer-types to the compiler flags. After doing that the kernel module seems to compile and work ok. Generally it is not a good idea to disable warnings, and the right way would be to fix the pointer type in the code, but it would enable you to proceed right away with your project until the code will have been fixed and updated on Github.

You can disable the warning by editing ~/nrc7292_sw_pkg/package/src/nrc/Makefile file and adding the mentioned compiler flag to the ccflags-y variable on the line 42, so that it would look like this:

ccflags-y += -Wall -Werror -Wno-incompatible-pointer-types

Hope this helps until the code is updated.

[mclendon99]

What I did is to change the declarations in nrc-netlink.c to use the "correct" type for the argument as follows:

#ifdef CONFIG_SUPPORT_NEW_NETLINK
static int nrc_nl_pre_doit(const struct genl_split_ops *ops,
struct sk_buff *skb, struct genl_info *info)
#else

Both functions simply return 0, so it's a fairly low risk change.

[k3rn3Lp4n1cK]

I compiled on 6.6 and works with @mclendon99 fix.
Although: insmod is failing

sudo insmod /home/pi/nrc_pkg/sw/driver/nrc.ko fw_name=uni_s1g.bin bss_max_idle=1800 ndp_preq=1 listen_interval=1000 bd_name=nrc7292_bd.dat
insmod: ERROR:  could not insert module /home/pi/nrc_pkg/sw/driver/nrc.ko: Invalid module format

[mclendon99]

I compiled on 6.6 and works with @mclendon99 fix. Although: insmod is failing

sudo insmod /home/pi/nrc_pkg/sw/driver/nrc.ko fw_name=uni_s1g.bin bss_max_idle=1800 ndp_preq=1 listen_interval=1000 bd_name=nrc7292_bd.dat
insmod: ERROR:  could not insert module /home/pi/nrc_pkg/sw/driver/nrc.ko: Invalid module format

You're not using the right kernel headers. Once you upgrade to 6.6, you must reboot, recompile nrc.ko with the correct kernel headers in /lib/modules/$(uname -r), and then insmod it. I'm on 6.6.28 now with no issues.

uname -r
6.6.28+rpt-rpi-v8
lsmod
Module Size Used by
sch_codel 16384 1
nrc 200704 0
mac80211 1040384 1 nrc
libarc4 12288 1 mac80211
pps_ldisc 12288 2
cmac 12288 3
algif_hash 12288 1
aes_arm64 12288 3
aes_generic 32768 1 aes_arm64
algif_skcipher 12288 1
af_alg 28672 6 algif_hash,algif_skcipher
bnep 24576 2
vc4 372736 4
brcmfmac_wcc 12288 0
hci_uart 49152 0
btbcm 24576 1 hci_uart
bluetooth 606208 26 hci_uart,btbcm,bnep
brcmfmac 348160 1 brcmfmac_wcc
binfmt_misc 16384 1
brcmutil 24576 1 brcmfmac
v3d 90112 0
snd_soc_hdmi_codec 20480 2
cfg80211 995328 3 nrc,brcmfmac,mac80211
gpu_sched 53248 1 v3d
drm_display_helper 16384 1 vc4
cec 53248 1 vc4
--- snip snip ---
cli_app
show config

---

[MAC Configuration]
Device Mode : STA
MAC Address : 84:25:3f:eb:41:04
Country : US
Bandwidth : 2M
Frequency : 9090 (14)
MAC80211_freq : 5765 (153)
Rate Control : ON
-MCS : 6
-bw : 2 Mhz (NRC Auto)
Guard Interval : AUTO
Security : OFF
RTS : OFF
RTS threshold : 0
Format : S1G
Preamble type : S1G_SHORT
Promiscuous Mode : OFF
color : 0x0
Auto CFO Cal : ON
BSSID : 84:25:3f:ab:17:8b
AID : 2

OK

[k3rn3Lp4n1cK]

Thanks, I just realized apt updated kernel to 6.6.31-v8+, but there are no kernel-headers in /usr/src.
Want to use ubuntu 22.04, but Raspi 5 doesn't officially support it because of the change in the physical header on the board.
I am using raspi 5 with raspbian 32bit OS

Thanks tho, I'll keep working it.