Arm64 cross-compiling

[gorghino]

Hi! I'm trying to cross-compile your drivers for my Jetson NX (arm64). I cannot directly use neither the install script nor the manual compilation on-board, since I'm testing the RealTime kernel.

On my host (x64 - Ubuntu 20.04.5 - gcc 9.4.0) I downloaded Nvidia's kernel sources and I compiled them.
The jetson NX has Ubuntu 20.04 (Jetpack 5.1) and I used toolchain 2020.08 (9.3.0) to compile the kernel sources in /media/gorgo/PopOS/home/gorgo/NX_5_1_HYAI/Linux_for_Tegra/source/public/kernel_out.

According to the Nvidia's documentation I shall be able to cross compile with

$ cd <path_to_module_source>
$ make ARCH=arm64 –C <kernel_directory> M=$(pwd)

after setting CROSS_COMPILE accordingly.

I tried:

gorgo@razer:~/8821cu-20210118$ make ARCH=arm64 CROSS_COMPILE=~/Downloads/l4t-gcc/bin/aarch64-buildroot-linux-gnu- -C /media/gorgo/PopOS/home/gorgo/NX_5_1_HYAI/Linux_for_Tegra/source/public/kernel_out M=$(pwd)
make: Entering directory '/media/gorgo/PopOS/home/gorgo/NX_5_1_HYAI/Linux_for_Tegra/source/public/kernel_out'
  MODPOST /home/gorgo/8821cu-20210118/Module.symvers
make: Leaving directory '/media/gorgo/PopOS/home/gorgo/NX_5_1_HYAI/Linux_for_Tegra/source/public/kernel_out'

Make stops after creating 4 files only (two are 0B):

-rw-rw-r--   1 gorgo gorgo    0 mar 29 10:07 modules.order
-rw-rw-r--   1 gorgo gorgo  121 mar 29 10:07 .modules.order.cmd
-rw-rw-r--   1 gorgo gorgo  212 mar 29 10:07 .Module.symvers.cmd
-rw-rw-r--   1 gorgo gorgo    0 mar 29 10:07 Module.symvers

In this log I retried the command with -d.
makefile.log

Thank you

[morrownr]

Hi @gorghino

You likely cannot use the installation script but that is no big deal.

For manually compiling, since I have made alterations to autodetect the platform, you will need to turn the autodetection off. Find the below lines in Makefile:

CONFIG_PLATFORM_AUTODETECT = y
CONFIG_PLATFORM_I386_PC = n

Change them to the following:

CONFIG_PLATFORM_AUTODETECT = n
CONFIG_PLATFORM_I386_PC = y

Try what you did again and let me know what happens. I did not test this but I do need to document what to do for cross-compiling so if we can work it out, I will document it.

[gorghino]

Hi @morrownr
I changed those lines in Makefile but I don't see a different output:

gorgo@razer:~/8821cu-20210916$ make ARCH=arm64 CROSS_COMPILE=~/Downloads/l4t-gcc/bin/aarch64-buildroot-linux-gnu- -C /media/gorgo/PopOS/home/gorgo/ORIN_5_1_1/Linux_for_Tegra/sources/kernel/kernel-5.10/ M=$(pwd)
make: Entering directory '/media/gorgo/PopOS/home/gorgo/ORIN_5_1_1/Linux_for_Tegra/sources/kernel/kernel-5.10'
  MODPOST /home/gorgo/8821cu-20210916/Module.symvers
make: Leaving directory '/media/gorgo/PopOS/home/gorgo/ORIN_5_1_1/Linux_for_Tegra/sources/kernel/kernel-5.10'

This is the same command with V=1

gorgo@razer:~/8821cu-20210916$ make V=1 ARCH=arm64 CROSS_COMPILE=~/Downloads/l4t-gcc/bin/aarch64-buildroot-linux-gnu- -C /media/gorgo/PopOS/home/gorgo/ORIN_5_1_1/Linux_for_Tegra/sources/kernel/kernel-5.10/ M=$(pwd)
make: Entering directory '/media/gorgo/PopOS/home/gorgo/ORIN_5_1_1/Linux_for_Tegra/sources/kernel/kernel-5.10'
test -e include/generated/autoconf.h -a -e include/config/auto.conf || (		\
echo >&2;							\
echo >&2 "  ERROR: Kernel configuration is invalid.";		\
echo >&2 "         include/generated/autoconf.h or include/config/auto.conf are missing.";\
echo >&2 "         Run 'make oldconfig && make prepare' on kernel src to fix it.";	\
echo >&2 ;							\
/bin/false)
make -f ./scripts/Makefile.build obj=/home/gorgo/8821cu-20210916 \
single-build= \
need-builtin=1 need-modorder=1
  {  :; } | awk '!x[$0]++' - > /home/gorgo/8821cu-20210916/modules.order
make -f ./scripts/Makefile.modpost
  sed 's/ko$/o/' /home/gorgo/8821cu-20210916/modules.order | scripts/mod/modpost -m  -E  -o /home/gorgo/8821cu-20210916/Module.symvers -e -i Module.symvers   -T -
make -f ./scripts/Makefile.modfinal
make: Leaving directory '/media/gorgo/PopOS/home/gorgo/ORIN_5_1_1/Linux_for_Tegra/sources/kernel/kernel-5.10'

The kernel_out folder has changed, but both contains Linux Kernel-5.10 sources

[morrownr]

I am going to reach out to another user that cross compiles to see if we can get some guidance. My to-do list is long right now so my time is limited. Will let you know.

[gorghino]

Tnks, no rush

[morrownr]

Here is the reply from @disaster123

I used the following command to cross compile the driver - for sure the pathes need to be adjusted and may be adapted to the environment:

ARCH=arm64 CROSS_COMPILE=/root/BPI-M4-bsp/toolchains/gcc-linaro-7.3.1-2018.05-x86_64_aarch64-linux-gnu/bin/aarch64-linux-gnu- make KVER=4.9.119-BPI-M4 KSRC=/root/BPI-M4-bsp/linux-rtk

If I had time right now, I would make a short guide for those using this and the drivers here. I think it could be specific to host x86 and target arm64. Would either or both of you gents like to work on it?