On 06/10/13 10:42, Peter Wu wrote: > On Monday 10 June 2013 07:56:01 Gerd Hoffmann wrote: >> On 06/08/13 23:49, Peter Wu wrote: >>> When QEMU starts, it always changes the serial port parameters including >>> baud rate. This confused my guest which thought it was outputting at 9600 >>> baud while it was in fact changed to 115200. >>> >>> >>> >>> After this patch, I can use `-serial /dev/ttyS0,baud=9600` to override the >>> default baud rate of 115200. >> >> I think we should just flip the default to 9600. IIRC this is the >> power-on default baud rate of the 8250 uart family, so this should be >> the qemu default too. If a guest wants to use a higher baudrate it has >> to reprogram the uart anyway (and qemu will apply the guest changes to >> the host uart). > > FWIW, when I tried MODE.COM in ms-dos to change the baud rate, `stty -F > /dev/ttyS0 -a` still reported 115200 baud. This is on Linux 3.9 if that > matters.
Hmm, with a linux guest changing the baudrate works just fine. Any chance mode.com takes a shortcut in case it thinks the rate didn't change? Does setting the speed first to 4800, then to 9600 work? > Besides this comment, any other feedback on the patch itself? Style is fine. But it appears to paper over some bug, and I'd prefer to find+fix the bug instead of allowing/requiring the user to set the baud rate manually to the correct value. cheers, Gerd
