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Date:      Sun, 10 Nov 2002 11:52:07 -0800
From:      David Schultz <dschultz@uclink.Berkeley.EDU>
To:        Mitsuru IWASAKI <iwasaki@jp.FreeBSD.org>
Cc:        bde@FreeBSD.ORG, stable@FreeBSD.ORG, current@FreeBSD.ORG
Subject:   Re: machdep.c problem
Message-ID:  <20021110195207.GA3323@HAL9000.homeunix.com>
In-Reply-To: <20021111.012625.74757276.iwasaki@jp.FreeBSD.org>
References:  <20021108234404.L22249-100000@server.arg.sj.co.uk> <20021110.050300.98560281.iwasaki@jp.FreeBSD.org> <20021110124354.GA2292@HAL9000.homeunix.com> <20021111.012625.74757276.iwasaki@jp.FreeBSD.org>

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Thus spake Mitsuru IWASAKI <iwasaki@jp.FreeBSD.org>:
> > This approach is okay with me in the sense that it doesn't break
> > anything that wasn't already broken, but as you say, I think we
> > can do better.  Below is a patch that merely extracts the basemem
> > size from the bootinfo structure for the purposes of mapping the
> > EBDA.  I retained the int 12h fallback just to be safe, but I
> > think the bootinfo structure is initialized with a valid basemem
> > for all loaders since at least 1998.  (Maybe the fallbacks in the
> > kernel should be removed entirely to avoid redundancy, or moved
> > from loader and boot2 to locore.s.)
> 
> Yes, this idea was in my first patch actually, and this was not
> good solution as Bruce explained.  Please see the archive at:
> http://docs.freebsd.org/cgi/getmsg.cgi?fetch=94412+0+archive/2002/freebsd-current/20021006.freebsd-current

It sounds like the basic objection is, ``We came up with this
feature in 1995 and never used it, so we shouldn't start using it
now.''  Fine, but I still maintain that determining the memory
size in real mode like everyone else is the right thing to do.
Are there any objections to the following?

	- Remove the redundant and unused memory detection code
	  from boot2, loader, and libi386.

	- Mark the bootinfo fields bi_basemem and bi_extmem as
	  deprecated.

	- Determine basemem in locore.s using 15h:e820h, with a
	  fallback to int 12h.

	- Remove the basemem calculation from machdep.c.

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