From 2ea26cf579c9defcf31e413e7c9b0fbc159237fc Mon Sep 17 00:00:00 2001 From: "Robert N. M. Watson" Date: Sun, 17 Aug 2014 19:43:28 +0000 Subject: [PATCH] Add a comment about an inherent race with hardware in the Altera JTAG UART's low-level console code. --- sys/dev/altera/jtag_uart/altera_jtag_uart_cons.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/sys/dev/altera/jtag_uart/altera_jtag_uart_cons.c b/sys/dev/altera/jtag_uart/altera_jtag_uart_cons.c index ae8459713003..96d20ceb21f4 100644 --- a/sys/dev/altera/jtag_uart/altera_jtag_uart_cons.c +++ b/sys/dev/altera/jtag_uart/altera_jtag_uart_cons.c @@ -221,6 +221,9 @@ aju_cons_write(char ch) * disconnection. * * XXXRW: The polling delay may require tuning. + * + * XXXRW: Notice the inherent race with hardware: in clearing the + * bit, we may race with hardware setting the same bit. */ v = aju_cons_control_read(); if (v & ALTERA_JTAG_UART_CONTROL_AC) {