Date: Wed, 04 Mar 1998 19:40:24 -0800 (PST) From: Simon Shapiro <shimon@simon-shapiro.org> To: Mike Smith <mike@smith.net.au> Cc: Matthew Thyer <Matthew.Thyer@dsto.defence.gov.au>, current@FreeBSD.ORG, Evan Champion <evanc@synapse.net> Subject: Re: silo overflows (Was Re: 3.0-RELEASE?) Message-ID: <XFMail.980304194024.shimon@simon-shapiro.org> In-Reply-To: <199803050248.SAA23631@dingo.cdrom.com>
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On 05-Mar-98 Mike Smith wrote: ... > Uh, the driver works just fine. Good! > However the driver has no say in the matter when _someone_else_ > disables interrupts for a long period of time, or when the hardware > fails to deliver them in the first place. Unless I misunderstand something, the driver should get interrupts delivered, unless another part of the kernel is in spltty(), or another spl which masks spltty. There should not be all that many of those, and they should be considered carefully. Now, if something in the kernel disables interrupts althogether for any amount of time, he should get the pointy hat everyone like to talk about so much, as this will make FreeBSD into a glorified Linux. > If you have a solution to this really quite challenging problem, I'm > sure we'd all be delighted to hear about it. Until then, please > believe me that there is nothing wrong with the driver, per se., which > "causes" these overflows. Again, don't decapitate me on this one, but does not the 16550 have a mode by which it will lower DSR and or CTS when the FIFO reaches a certain point of saturation? This will stop the modem from transmitting characters within one character time period. Any modem which will not do that is very broken. This i have done suvvessfully on a Z-80, using a Z80-SIO USART ( a cusin of the 8250 if i remember right). There are other, ugly hacks to be done to guarantee delivery but they are not worth it. > > Just incidentally, the P6 has relatively poor I/O performance, > particularly when it comes to talking to ISA peripherals. Yes, but faster than an 8080A + 8250. Agree? Simon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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