Date: Mon, 18 Jun 2007 08:59:15 +0200 From: Christian Kandeler <christian.kandeler@hob.de> To: freebsd-hackers@freebsd.org Subject: Re: Question about serial console code Message-ID: <200706180859.15865.christian.kandeler@hob.de> In-Reply-To: <8D1F83C2-C7A6-4C86-88BE-17DD516DA4D9@mac.com> References: <200706151541.51913.christian.kandeler@hob.de> <8D1F83C2-C7A6-4C86-88BE-17DD516DA4D9@mac.com>
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On Friday 15 June 2007 18:03, Marcel Moolenaar wrote: > The loop is formed by the transmit interrupt of the UART. > When UART_TRANSMIT() is called, the FIFO of the UART is > written and transmission starts. Eventually the UART will > raise a "transmission done" interrupt, which will trigger > the next iteration. I see. However: > If the UART has no FIFO (in the 16550-sense), then sc_txfifosz > is still 1. But where is this set? The ns8250_bus_probe() function returns early when it detects a FIFO-less device, leaving sc_txfifosz at its pre-initialized value (i.e. zero). And it doesn't seem to get set anywhere else, either. Regards, Christian Kandeler
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