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Date:      Sat, 07 Feb 1998 14:54:53 -0800
From:      Mike Smith <mike@smith.net.au>
To:        hackers@FreeBSD.ORG
Subject:   Bootblock sizes (was bad144 ravings)
Message-ID:  <199802072254.OAA07140@dingo.cdrom.com>

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Ok, just to put some perspective on things, so that people understand 
the situation.

The issue at hand here is the size of the 'boot2' file, which may not 
exceed 14 sectors @ 512B each (in order to fit on a 15spt disk), or 
7168 bytes.

Let us look at some sizes (in bytes).  The 'Bare' bootblock has serial 
console support, but nothing else fancy.  

Config			Size		Feature bulk
------			----		------------
Bare			6560		0 (room for 608 bytes)
With bad144		7104		544
With extras		6640		80
With splash + extras	6768		208 (80 + 128)
With VESA		6624		64
With NAMEBLOCK		6640		80
With NAMEBLOCK and
  NAMEBLOCK_WRITEBACK	6640		80

The 'extras' feature allows arbitrary loading of extra items which can 
be recovered later within the kernel.  You can use this for PnP tables, 
userconfig scripts, whatever.  NAMEBLOCK and VESA are features really 
of interest only to specific users; they're listed here just for 
interest's sake.

No conclusions here, this is just for information's sake.

-- 
\\  Sometimes you're ahead,       \\  Mike Smith
\\  sometimes you're behind.      \\  mike@smith.net.au
\\  The race is long, and in the  \\  msmith@freebsd.org
\\  end it's only with yourself.  \\  msmith@cdrom.com





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