Date: Fri, 8 Jan 1999 01:46:35 +0200 (EET) From: Heikki Suonsivu <hsu@clinet.fi> To: freebsd-bugs@FreeBSD.ORG Subject: Re: i386/9341: tty-level buffer overflows Message-ID: <199901072346.BAA10849@katiska.clinet.fi>
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Nate Williams <nate@mt.sri.com> writes: > > > I'll bet you have crappy UARTS that claim to be 16550's, but in fact are > > > some sort of clone that doesn't work well. That UARTS on my laptop are > > > not real either, although I get about 57600 on it w/out problems. > > > > > > And, a 486/25 is not exactly a speed daemon. :) > > > > It's an IBM ThinkPad 350C, if that tells anyone anything. > > I wouldn't be surprised at all if they were crappy UARTS, and you ain't > > gotta tell ME 486/25 is slow (I run X on it, after all... ;), but c'mon; > > this is *19,200* baud!! I'd think even a 486/25 should be able to handle > > that without puking this much. > > With crappy UARTS you're lucky to get 9600 baud if you've got X on the > box. This is tty-level buffer overflow problem, not a problem with serial fifo overflows (which is different I think ?). If it was a serial fifo overflow problem, changing TTYHOG and RS_IBUFSIZEs would not help, but it does, on all hosts I have had problems with. These are various 386 and 486 boxes. I do not know (remember) if pentiums have this problem, as all my kernels have had this patch for years. I still run into this problem occasionally when installing a slow host via a serial connection. Installation floppy kernel obviously does not contain the fix, and thus the first installation is *slow*, but problem goes away after getting the kernel compiled with the patch. I assume the problem is dependent on not just the serial ports but also the other hardware in the host, like PIO ethernet boards and stuff like that, as not everyone seems to see it. -- Heikki Suonsivu / Clinet Oy / Tekniikantie 12 / FI-02150 Espoo / FINLAND, hsu@clinet.fi mobile +358-40-5519679 work +358-9-43542270 fax -4555276 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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