*BSD News Article 94185


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From: dillon@flea.best.net (Matt Dillon)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: 256M RAM question
Date: 22 Apr 1997 11:42:56 -0700
Organization: BEST Internet Communications, Inc.
Lines: 28
Message-ID: <5jj0rg$ld7@flea.best.net>
References: <335CF65C.4435@sonic.net> <5jiv5o$le9$1@bofh.noc.best.net>
NNTP-Posting-Host: flea.best.net
Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:39541

:In article <5jiv5o$le9$1@bofh.noc.best.net>,
:Ron Echeverri <rone@bofh.noc.best.net> wrote:
:>In article <335CF65C.4435@sonic.net>, Eric J. Rossin <ejr@sonic.net> wrote:
:>>I have a machine with 256M RAM. I re-built a kernel to set the
:>>MAXMEM option, but when I set it to 256*1024, the boot hung
:>>(something about allocating bounce buffers? I don't re-member
:>>the exact message, but could re-create it if it is needed). I then
:>>changed it to 192*1024, and the system runs fine (with 192M RAM).
:>>Is this a memory problem with my system, a bug, or a setup problem?
:>
:>I think it's a bug.  You should take BOUNCE_BUFFERS out of your kernel
:>config; it doesn't seem to like 256MB of RAM.
:>
:>rone
:>-- 
:>Ron Echeverri         Best Internet Usenet Administration         rone@best.net

    As far as we can tell, when you have that much memory, certain dynamically
    sized data structures allocated by the kernel before the bounce buffers 
    go past the 16 MByte mark, causing the bounce buffers to be allocated at
    out-of-range addresses.

    If you do not have any ISA cards that require DMA, you can turn off
    the BOUNCE_BUFFERS option.  E.G. since our ethernet and disk controllers
    are PCI, we didn't need the option so we just turned it off.

					-Matt