[RT-AC86u] USB video class modules load trouble

[Iojkin_kot]

I compiled USB video class kernel modules from repository https://github.com/RMerl/asuswrt-merlin.ng. Compiling is ok, but when i try to load modules i get error:

insmod /opt/lib/modules/4.1.27/kernel/drivers/media/v4l2-core/videobuf2-core.ko
Nov 15 12:57:12 kernel: videobuf2_core: Unknown symbol dma_buf_get (err 0)
Nov 15 12:57:12 kernel: videobuf2_core: Unknown symbol dma_buf_put (err 0)
Nov 15 12:57:12 kernel: videobuf2_core: Unknown symbol dma_buf_fd (err 0)

What i do wrong?

Firmware Version:384.7_2

 

[Iojkin_kot]

Anyone help me? In other forums only questions about this error, but no solution...

 

[Odkrys]

Did you enable CONFIG_DMA_SHARED_BUFFER=y ?

 

[Iojkin_kot]

Yes, I compiled kernel with CONFIG_DMA_SHARED_BUFFER=y. But Merlin compiled his firmware without this option. Maybe this is the problem?

 

[RMerlin]

Some modules will generate changes in other kernel components that make it impossible to just insert the module in an existing kernel - sometimes you have to recompile the whole kernel as well. And some of these changes may conflict and break existing precompiled modules, so be warned that you are walking in a minefield whenever playing with kernel options.

 

[Iojkin_kot]

OK I understood. Can you compile your firmwares with CONFIG_DMA_SHARED_BUFFER=y? Or should I rebuild the firmware each time to support this option?

 

[RMerlin]

I see no reason to compile the firmware with that option enabled. You will have to compile your own build if you have particular needs for that specific option - and hope that it doesn't prevent the kernel from booting other precompiled modules.