4 ms·
Since I once had the case where junk on the line (from a wiggly connection) caused Magic Sysrq requests I'm fully on your side. No junk tolerated for potential
by jaeckel 5mo ago
Since I once had the case where junk on the line (from a wiggly connection) caused Magic Sysrq requests I'm fully on your side. No junk tolerated for potential hot plug connections.
- foresto 5mo agoWhat byte sequence on a Tx/Rx/Gnd serial line can trigger Sysrq key sequences?
- eqvinox 5mo agoIt's not a byte sequence, it's a BREAK == pulling the line low for longer than a byte, i.e. invalid serial framing on the stop bit.
- foresto 5mo agoI'm aware of serial breaks, but this is the first I've heard of them being interpreted as SysRq by Linux. That could be handy. Thanks for the tip. I assume the possibility of spurious Rx state is why FTDI chose to wire Rx to the tip pin of the female TRS connector: It's the last pin to make contact with anything when plugging in, and therefore least likely to be bridged to ground. I suppose the mechanical design of any particular jack would determine whether it's possible at all.