Assistance Needed: Issue with Nexmon CSI on BCM4358 (Samsung Galaxy S7 SM-G930F)

[giovanihoff]

Dear Nexmon Team,

First, I want to thank you for the incredible work you've done with the Nexmon CSI project. It’s truly an impressive contribution to the field, and I appreciate all the effort that went into its development.

I’ve been working on implementing Nexmon CSI on a Samsung Galaxy S7 (SM-G930F) with a BCM4358 chipset. I’ve followed all the steps in the "Getting Started" guide and successfully installed the modified firmware. I was able to confirm that the firmware is correctly applied with the following command:

adb shell su -c "strings /vendor/firmware/fw_bcmdhd.bin | grep nexmon"

The output confirmed that the firmware version is 7.112.300.14 (nexmon.org/csi: fdb2-dirty-2). However, I’m encountering an issue when attempting to use nexutil to interact with the firmware. Specifically, the following commands return an error:

adb shell su -c "/data/local/tmp/nexutil -m"

Output:

__nex_driver_io: error ret=-1 errno=13 monitor: 0

I also tried to start capturing CSI data:

adb shell su -c "/data/local/tmp/nexutil -I wlan0 -s500 -b -l34"

This command similarly returns:

__nex_driver_io: error ret=-1 errno=13

I confirmed that:

• The device is rooted and running with uid=0(root);
  

• The Wi-Fi interface wlan0 is operational and connected to a network (ifconfig wlan0 shows it as UP);
  

• I’ve reinstalled the firmware multiple times using make install-firmware, and the process completes without errors;
  

• The nexutil binary is correctly installed and has the appropriate permissions.
  

Additionally, I’ve checked the system logs (dmesg) and couldn’t find any entries explicitly related to Nexmon or CSI. I’ve also ensured that all submodules of the Nexmon repository were properly initialized and updated (git submodule update --init --recursive).

Despite these efforts, I haven’t been able to successfully place the device in monitor mode or capture CSI data. I suspect there might be a specific issue with the interaction between nexutil and the modified driver, but I’m unable to identify the root cause.

Could you kindly provide guidance on what might be causing this issue or suggest additional steps to troubleshoot? I’d be happy to provide logs or any other information that might be helpful.

Note: I also have a Galaxy S8, SM-G950FD if you are interested in carrying out more tests.

Thank you so much for your time and assistance!

Best regards,

Giovani Hoff

[jlinktu]

Hi Giovani,

I’ve been working on implementing Nexmon CSI on a Samsung Galaxy S7 (SM-G930F) with a BCM4358 chipset.

Are you sure your device comes with a bcm4358? AFAIK the Samsung Galaxy S7 features a bcm43596a0.

[jlinktu]

The Nexmon CSI README lists the currently supported devices:

• Googles Nexus 5 (bcm4339)
• Raspberry Pi 3B+ and 4 (bcm43455c0)
• Google Nexus 6P (bcm4358)
• and Asus RT-AC86U (bcm4366c0)

Hence, the patch doesn't support the Samsung Galaxy S7 (bcm43596a0) in its current form. But it could be ported to work with firmwares for the bcm43596a0.

[giovanihoff]

The Nexmon CSI README lists the currently supported devices:

• Googles Nexus 5 (bcm4339)
• Raspberry Pi 3B+ and 4 (bcm43455c0)
• Google Nexus 6P (bcm4358)
• and Asus RT-AC86U (bcm4366c0)

Hence, the patch doesn't support the Samsung Galaxy S7 (bcm43596a0) in its current form. But it could be ported to work with firmwares for the bcm43596a0.

@jlinktu,

Thank you for clarifying that the nexmon_csi does not currently support the Samsung Galaxy S7 (bcm43596a0). I am interested in attempting this adaptation, but I will need help.

Please, could you kindly provide more specific guidance on how to proceed with this adaptation? Any detailed instructions, resources, or steps would be greatly appreciated, as I would like to try implementing this.

Thank you for your time and support!

Best regards,

[giovanihoff]

Please, I would like to clarify a question about the compatibility of the Nexus 6P with Nexmon CSI. The documentation states that it is compatible, but I think that the Nexus 6P uses the Qualcomm WCN3660 chip, not the Broadcom BCM 4358. Could you confirm if the Nexus 6P is truly compatible with the project? Thank you!

[jlinktu]

Yes, the Google Nexus 6P comes with a BCM4358 (also see this ifixit teardown).

[giovanihoff]

Perfect. Thank you for the prompt and clear clarification regarding the device compatibility. Your guidance has been invaluable to us.

We are now planning to buy a Nexus 6P and will proceed with the necessary tests as outlined. Looking forward to sharing further progress with you.

Best regards,