Date: Sat, 06 Sep 1997 00:53:38 -0600 From: Brett Glass <brett@lariat.org> To: cdillon@tri-lakes.net, arg@arg1.demon.co.uk Cc: freebsd-hardware@FreeBSD.ORG Subject: RE: Problems with 16650 UARTs Message-ID: <3.0.3.32.19970906005338.008a3d40@mail.lariat.org> In-Reply-To: <8825650A.000FD662.00@IWNS2.infoworld.com>
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At 08:49 PM 9/5/97 +0000, cdillon@tri-lakes.net wrote: I've been working on an x86-specific, highly-tuned driver that's designed to work only with permanently-attached '550 or better UARTs. (Right now, it doesn't support shared IRQs, but I'm looking at ways to add this feature without killing efficiency.) The new driver uses code I developed years ago for the PC/AT, where timing was everything. It enables interrupts only when the port isn't receiving, and switches seamlessly to timer-driven polling when characters are streaming in. Overhead is about the lowest it can be given the data structures involved. (I'm using some code sequences that GCC never seems to generate.) Will publish this when it gets closer to production quality, and when I've got more confidence that I understand the kernel stuff. --Brett P.S. in anticipation of flames: I know that some folks will want (or need!) to stay with sio, but this driver will be good for those who need bleeding-edge speed on Intel platforms (e.g. ISPs using FreeBSD as a zillion-port terminal server). At 08:49 PM 9/5/97 +0000, you wrote: >Bingo... I have been plagued with this same problem for some time, but >thought it was just my lousy, clueless ISP at the root of it all (uses NT >of all things... and Telebit Netblazer term servers. Are those any good?). >I run 2.2-STABLE (recently cvsupped and made world) with userland ppp on an >internal USR Sportster 33k6 with the port locked at 115200 using hardware >flow control. I can be chatting on IRC, browsing web pages, and downloading >some mail when all incoming data comes to a halt (even sometimes when just >doing nothing). The only fix seems to be to kill the ppp session and dial >in again (I usually just 'quit' and then run userland ppp all over again). >I know that outgoing packets still work because anything I type in an IRC >channel makes it out into the world.. I just don't get anything back. >I don't know if this means much, but it almost ALWAYS happens when I get >my mail, as this initially made me think it was just some anomaly >between my ISP's mail server and the terminal server. It happened most >often with Netscape's POP3 client and with popclient, but almost never with >XFMail's POP3 client. > >--- Chris Dillon >--- cdillon@tri-lakes.net >--- Powered by FreeBSD, the best free OS on the planet >---- (http://www.freebsd.org) > > > >
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