On (09/05/19 13:14), Steven Rostedt wrote: > > Hmm, from the article, > > > > https://en.wikipedia.org/wiki/Universal_asynchronous_receiver-transmitter > > > > "Since transmission of a single or multiple characters may take a long time > > relative to CPU speeds, a UART maintains a flag showing busy status so that the > > host system knows if there is at least one character in the transmit buffer or > > shift register; "ready for next character(s)" may also be signaled with an > > interrupt." > > I'm pretty sure all serial consoles do a busy loop on the UART and not > use interrupts to notify when it's available. Yes. Besides, we call console drivers with local IRQs disabled. -ss
