Date: Tue, 4 Jul 1995 15:55:36 +1000 From: Bruce Evans <bde@zeta.org.au> To: babkin@hq.icb.chel.su, davidg@Root.COM Cc: hackers@freebsd.org Subject: Re: Minor for Digiboard driver Message-ID: <199507040555.PAA11661@godzilla.zeta.org.au>
next in thread | raw e-mail | index | archive | help
>>My developing of Digiboard driver came to the point where I need >>a major number. Give me one please. > Just pick the next available one. If we need to re-assign it before >committing the driver (very unlikely), then that's okay. We're close to needing a single major number for all ttys (like sd has a single major number for all scsi controllers). You need a new major now, however. Please be careful not to implement any ioctl or minor number magic that is inconsistent with the other drivers (sio, cy and rc; cx and ity are already inconsistent). Did you use any "intelligent" features of the Digiboard? Minor design flaws made most of the cd1400 (the serial chip on Cyclades boards) intelligence that was was using quite useless: I was using the cd1400's POSIX handling of parity and framing errors but found that this interferred with the reporting of overrun errors. I was using the cd1400's match-on-special-char feature to detect packet framing characters but found that the extra interrupts for the special characters caused overrun errors. I thought had the cd1400 working slightly more efficiently than a 16550, but that was only with an input fifo size that was too large to avoid overruns. To avoid overruns for just 2 active ports, the input fifo size has to be 6, while 14 works for 16550's and is considerably more efficient. Bruce
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199507040555.PAA11661>