ktrace -di of the process will show what is going on
Crystal Kolipe <kolip...@exoticsilicon.com> wrote: > On Thu, Oct 26, 2023 at 12:20:08PM -0400, Morgan Aldridge wrote: > > Yes, your assumption was correct, every keypress acts as if I had pressed > > enter. Thanks for confirming! > > Getty re-displays the login prompt when it sees either 0x00 or 0x80 on the > serial line. In fact, you can do it from the normal framebuffer console too, > just hit control-@ at the login prompt and it should repeat. > > (This is a historic behaviour which was once used for semi-automatic baud rate > selection where you hit 'BREAK' a few times to get the remote end to cycle > through all the speeds it supported until you, (hopefully), got a login > prompt). > > So in your case, it seems that either the terminal is putting something on the > serial data lines that the USB serial adaptor is interpreting as nulls, or > possibly it's doing something with the handshaking lines that makes the > USB serial adaptor generate the equivalent internally. > > Any extra nulls added as padding bytes probably wouldn't show up in the > loopback test either, because the terminal would just happily ignore them. >
