From owner-freebsd-hardware  Tue Mar 28 14:20:10 2000
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Date: Wed, 29 Mar 2000 00:19:43 +0200
From: "Jose M. Alcaide" <jose@we.lc.ehu.es>
Organization: Universidad del =?iso-8859-1?Q?Pa=EDs?= Vasco - Dpto. de Electricidad y 
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To: Bruce Evans <bde@zeta.org.au>
Cc: freebsd-hardware@FreeBSD.ORG
Subject: Re: [fix and RFC] interrupt-level buffer overflows with Xircom 
 PCMCIAmodem
References: <Pine.BSF.4.21.0002130354510.3031-100000@alphplex.bde.org>
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Bruce Evans wrote:
> 
> On Sat, 12 Feb 2000, Jose M. Alcaide wrote:
> 
> > the addition of a new kernel configuration option for permitting
> > to change RS_IBUFSIZE to any desired value.
> 
> RS_IBUFSIZE doesn't exist in -current.  Instead, the buffer is sized to
> hold 4 ticks (4.0 / hz seconds) worth of input at the current input speed
> (or 128 bytes if that is larger).
> 

Six weeks passed after this issue was discussed in -hardware. I come
back because finally I installed 4.0-RELEASE on my laptop, so that I
could test the new sio(4) dynamic buffer sizing with the Xircom Realport 56
pccard modem, which has a broken 16550 emulation.

At 115200, ibufsize is 512, and the buffer overflows still happen.
I experimentally determined that the overflows dissapear when I modify
the ibufsize computation, doubling the buffer size (i.e., ibufsize=1024
at 115200). Just FYI, Bruce.

Cheers,
-- JMA

 **** Jose M. Alcaide  //  jose@we.lc.ehu.es  //  jmas@FreeBSD.org ****
 "Beware of Programmers who carry screwdrivers"  --   Leonard Brandwein


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