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Date: Sun, 16 Apr 1995 22:39:39 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199504161239.WAA08936@godzilla.zeta.org.au>
To: bde@zeta.org.au, davidg@Root.COM
Subject: Re: cvs commit: src/sys/i386/i386 locore.s
Cc: CVS-commiters@freefall.cdrom.com, cvs-sys@freefall.cdrom.com
Sender: commit-owner@FreeBSD.org
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>>>  Modified:    sys/i386/i386 locore.s
>>>  Log:
>>>  Remove gratuitous waste of 2K of memory for BIOS variables. We never load
>>>  the kernel at 0-640k; we haven't had the ability to do that since before
>>...
>>boot.c has `#ifdef REDUNDANT' code to skip over the "BIOS variables" between
>>(startaddr + 0x400) and (startaddr + 0x4ff) even when startaddr != 0.
>>Removing the padding is a bit dangerous because bootstraps older than approx.
>>1995/01/25 don't have `#ifdef REDUNDANT' so they depend on the padding.

>   This would skip over the movw instruction at the beginning (which wouldn't
>set the warmstart).

No, the movw is in the first 0x400 bytes that gets loaded.  Only 0x100
bytes gets skipped.

>With the new boot structure, numerous changes to the
>startup flags, etc, we more or less require people to update the bootblocks
>anyway. I don't think this is a problem.

We should require this (now and in future), and remove all of the forwards
compatibility cruft from locore.s.

Bruce