Ver 1.8.1 crashes when enabling CONFIG_SERIAL_DMA

Hi,
I’m reading data from external source on Serial 4/5 inputs of Pixhawk 2. (fmu-v3)
In order to get the best rate i have to enable DMA on those uarts.
I enabled two config options in nsh defconfig:
CONFIG_UARTx_RXDMA fir specific port, and CONFIG_SERIAL_DMA that enables DMA for serial communication.
The CONFIG_SERIAL_DMA causes the system crash on opening uart.
Why?