which usart is used for bootloader in F103RC ?

Hello dear forum,

In my F103RC project I need to connect USART inputs RX2 and RX1 to each other

( I have my PCB produced already, thats why )

I want use flash loader demo with USART1 

my question ;

which usart is used other than USART1 during bootloader function

does RX2 have a function during bootload ? - ( I want it to be floating input without a function during bootload )

is this possible ?

thank you