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From: "John S. Dyson" <toor@dyson.iquest.net>
Message-Id: <199609070350.WAA02660@dyson.iquest.net>
Subject: Re: CCD Setup woes ... (Kernel Panic)
To: gordon@drogon.net (Gordon Henderson)
Date: Fri, 6 Sep 1996 22:50:07 -0500 (EST)
Cc: questions@freebsd.org, scsi@freebsd.org
In-Reply-To: <Pine.LNX.3.91.960906150432.342A-100000@unicorn> from "Gordon Henderson" at Sep 6, 96 04:54:34 pm
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> 
> I'm tring to get a CCD going as an experiment and it's causing the kernel
> to panic. 
> 
Yep, there is a problem with CCD using the FreeBSD bounce scheme.  Of course,
it is only noticed on ISA systems.

> 
> which resulted in a kernel panic. The message is:
> 
>   vm_bounce_alloc: b_bufsize(0x80) < b_count(0x200) !!
>   panic: vm_bounce_alloc
> 
b_bufsize is not being setup correctly in ccd (I think).

>
> followed by the usual syncing disks bit. The number in the b_bufsize() 
> varies from crash to crash.
> 
> Am I doing anything obviously wrong?
> 
No.

Hope the following works for you!!!  If it does, let me know so that
I can commit it.

Try this patch to ccd relative to -current (the equiv patch might
work for -stable), I haven't tested this though:


Index: ccd.c
===================================================================
RCS file: /local/home/ncvs/src/sys/dev/ccd/ccd.c,v
retrieving revision 1.16
diff -C5 -r1.16 ccd.c
*** ccd.c	1996/07/24 23:45:24	1.16
--- ccd.c	1996/09/07 03:46:27
***************
*** 909,918 ****
--- 909,920 ----
  	else
  		cbp->cb_buf.b_bcount = dbtob(cs->sc_ileave - cboff);
  	if (cbp->cb_buf.b_bcount > bcount)
  		cbp->cb_buf.b_bcount = bcount;
  
+ 	cbp->cb_buf.b_bufsize = cbp->cb_buf.b_bcount;
+ 
  	/*
  	 * context for ccdiodone
  	 */
  	cbp->cb_obp = bp;
  	cbp->cb_unit = cs - ccd_softc;