From owner-freebsd-hackers  Tue Nov  9  7:56: 3 1999
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To: hackers@freebsd.org, peter@freebsd.org
Subject: How does sio handle full clists?
Date: Tue, 09 Nov 1999 10:55:52 -0500
From: Brian McGovern <bmcgover@cisco.com>
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I've been digging around in the sio driver, trying to find out how it handles
receive interrupts when the clists are full.

What I think I found (which is why I'm asking) is that if an RX interrupt
occurs, and the clists are full and the driver can't offload all of the
data from the UART, it disables the interrupts.

I assume that at some later point (I haven't quite nailed this down), 
interrupts get enabled again, which will generate a fresh interrupt from the
data that is still stored on the UART.

I guess I'm looking for confirmation of this, and, if I'm way off, maybe a 
quick explanatio of what _really_ happens. I'm looking at trying to reuse
the behavior elsewhere, so I want a good understanding of the process before I
get myself in to too much trouble.
	-Brian


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