From owner-freebsd-hackers  Thu Nov 13 10:17:08 1997
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From: mouth@ibm.net (John Kelly)
To: Bruce Evans <bde@zeta.org.au>
Cc: hackers@FreeBSD.ORG
Subject: Re: Status of 650 UART support
Date: Thu, 13 Nov 1997 19:18:08 GMT
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On Thu, 13 Nov 1997 20:35:53 +1100, Bruce Evans <bde@zeta.org.au>
wrote:

>>Why can't we handle large bursts of input?
>
>Buffer sizes are finite.

Can't we use malloc to create elastic buffers on the fly?  Is that a
no-no in the kernel?

>Multiply some of these numbers by 4 for 64-bit fifos and you have
>seriously high (normal worst case) latencies.  (My definition of ``high''
>is anything that would stop an 8250 from working at 115200 bps - 87
>usec :-).  I will reduce this when faster speeds become common.)

Why not start from scratch and develop siov2.c which uses elastic
buffers, 650 polled vs. interrupt mode switching,  yada, yada, yada.
Sio.c could still be the default while siov2.c could be selected on a
port by port basis with a kernel config flag.

Now if someone foolhardy enough to undertake such a project would step
forward (don't look in my direction, I know better).  ;-)

John