Subject: Re: serial port silo overflow repair
To: None <>
From: Gordon W. Ross <>
List: tech-kern
Date: 07/30/1997 00:37:41
> From: "Erik E. Fair" (Timekeeper) <>
> Cc: tech-kern@NetBSD.ORG
> Date: 	Tue, 29 Jul 1997 01:30:18 -0700
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> Sender: tech-kern-owner@NetBSD.ORG
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> See PR#3239 (a SPARC ELC)
> This has been a recurring problem for the ports whose mailing lists I read
> over a very long period of time (a few years):  port-sparc, port-sun3,
> port-mac68k (especially this last).
> 	Erik E. Fair

The sun3 serial port driver uses a two-level interrupt scheme
(and PDMA) which makes "silo overflow" events rare.  There were
problems with H/W flow control until somewhat recently, but
other than that I've not not heard many complaints.

Note that the sparc does not use the same driver, and the
mac68k does not have H/W interrupt assignments that allow
reliable handling of serial port PDMA (or so I've heard).