2400879_en-US

[#1]

Issue: CONFIG_IMX_RPMSG_TTY is built as a module but appears as "not set" after flashing Android

Hi NXP Team,

I am working on the i.MX8M Mini LPDDR4 EVK with the Android 16 BSP and trying to enable RPMsg communication between the Cortex-A53 and Cortex-M4.

Configuration

I enabled the NXP RPMsg TTY driver in the kernel configuration:

CONFIG_IMX_RPMSG_TTY=m

I also added the module to SharedBoardConfig.mk:

$(KERNEL_OUT)/drivers/rpmsg/imx_rpmsg_tty.ko

The module is built successfully.

The generated kernel configuration confirms it is enabled:

grep CONFIG_IMX_RPMSG_TTY out/target/product/evk_8mm/obj/KERNEL_OBJ/.config

Output:

CONFIG_IMX_RPMSG_TTY=m

The module is also generated successfully:

out/target/product/evk_8mm/vendor_dlkm/lib/modules/imx_rpmsg_tty.ko

and is packaged into the Android image.

Runtime Observation

After flashing the board, the running kernel configuration does not report the RPMsg module configurations.

adb shell zcat /proc/config.gz | grep RPMSG

Output:

CONFIG_GKI_HIDDEN_RPMSG_CONFIGS=y
# CONFIG_RPMSG_WWAN_CTRL is not set
# CONFIG_RPMSG_TTY is not set
# CONFIG_SND_SOC_FSL_RPMSG is not set
CONFIG_RPMSG=y
CONFIG_RPMSG_CHAR=y
# CONFIG_RPMSG_CTRL is not set
# CONFIG_RPMSG_NS is not set
# CONFIG_RPMSG_QCOM_GLINK_RPM is not set
# CONFIG_RPMSG_VIRTIO is not set

Also,

adb shell zcat /proc/config.gz | grep IMX_RPMSG

returns no output.

However, the corresponding RPMsg modules are loaded successfully:

lsmod | grep -i rpmsg

Output:

snd_soc_imx_rpmsg
snd_soc_rpmsg_ak4497
imx_audio_rpmsg
snd_soc_fsl_rpmsg
imx_pcm_rpmsg
i2c_rpmsg_imx
virtio_rpmsg_bus
rpmsg_ns

This indicates that the modules are built and loaded correctly, but /proc/config.gz does not reflect their configuration.

Questions

1. Is it expected that /proc/config.gz on the Android 16 BSP only reflects the base GKI kernel configuration and not the vendor module configuration?
2. Why is CONFIG_IMX_RPMSG_TTY=m not visible in /proc/config.gz even though imx_rpmsg_tty.ko is built and packaged?
3. Is there an additional configuration required for the running kernel configuration to include vendor module options?
4. Could this behavior be related to Android GKI and vendor_dlkm module packaging?

Any clarification would be appreciated.

Androidi.MX 8M | i.MX 8M Mini | i.MX 8M NanoRe: Issue: CONFIG_IMX_RPMSG_TTY is built as a module but appears as "not set" after flashi

Hello @vp1 

Hope you are doing very well.

Could you please share what device tree are you using?

Can you please try using the imx8mm-evk-rpmsg.dts?

Best regards,

Salas.

Re: Issue: CONFIG_IMX_RPMSG_TTY is built as a module but appears as "not set" after flashi

Hi @Manuel_Salas ,

Thank you for your response.

Currently, my Android AOSP build is using the device tree imx8mm-evk.dts. I can see that imx8mm-evk-rpmsg.dts is also available and is built successfully.

Could you please let me know how to configure the Android build to use imx8mm-evk-rpmsg.dts instead of imx8mm-evk.dts during boot?

Is there any specific configuration in the Android BSP, U-Boot, or imx-mkimage that selects which device tree is packaged and loaded?

Thank you for your guidance.

Best regards,
Vikas Patil