I have some confusions below: if the UART has a byte to read,so an interrupt is executing,when should I clear the RX mask? if at the beginning,what will happen when a new rx interrupt is generated while current one has not finished yet? if at the end,new interrupts may be missed.Two bytes are received(two inttrupts should have been generated) when last interrput is not finished.Then I will miss a byte. Which way is better? I've read some codes,disable the interrupt at the beggining of the irq handler and enable at the end.Under what situations should I do like this?

What should I pay attention to when UART interrupts are used?

I have some confusions below:

if the UART has a byte to read,so an interrupt is executing,when should I clear the RX mask?

if at the beginning,what will happen when a new rx interrupt is generated while current one has not finished yet?
if at the end,new interrupts may be missed.Two bytes are received(two inttrupts should have been generated) when last interrput is not finished.Then I will miss a byte.

Which way is better?

I've read some codes,disable the interrupt at the beggining of the irq handler and enable at the end.Under what situations should I do like this?