Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32f3/STM32F302/TIM8/OR#0x0
option registers
TIM8_ETR_ADC2 remapping capability
TIM8_ETR_ADC3 remapping capability
https://github.com/modm-io/cmsis-svd-stm32