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Date:      Fri, 4 Dec 1998 12:28:57 -0800 (PST)
From:      Archie Cobbs <archie@whistle.com>
To:        freebsd-hackers@FreeBSD.ORG
Subject:   Help with clist_alloc_cblocks()
Message-ID:  <199812042028.MAA06497@bubba.whistle.com>

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Hello,
I'm trying to write a line discipline, roughly similar to the PPP
line discipline. My question is, what are the correct parameters to
give to clist_alloc_cblocks()?

  /*
   * Pre-allocate cblocks to the an appropriate amount.
   */

    ttyflush(tp, FREAD | FWRITE);
    clist_alloc_cblocks(&tp->t_canq, 0, 0);
    clist_alloc_cblocks(&tp->t_rawq, 0, 0); 	/* XXX probably wrong! */
    clist_alloc_cblocks(&tp->t_outq, MLEN + NGT_HIWATER, MLEN + NGT_HIWATER);

I'm not sure how to determine what the correct values to call
clist_alloc_cblocks() should be. The values I'm using now cause a
bunch of "interrupt-level buffer overflows" reported from the sio
driver. It looks like I can simply increase the values for tp->t_rawq
but I'd like to understand exactly what they mean first.

Thanks,
-Archie

___________________________________________________________________________
Archie Cobbs   *   Whistle Communications, Inc.  *   http://www.whistle.com

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