DragonFly commits List (threaded) for 2009-03
DragonFly BSD
DragonFly commits List (threaded) for 2009-03
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Re: DragonFly-2.3.0.337.gd64b2 master lib/libstand hammerread.c sys/boot/common boot2.h dinode.h ufsread.c sys/boot/pc32/boot2 Makefile boot1.S boot2.c sys/boot/pc32 bootasm.h sys/sys types.h


From: Bill Hacker <wbh@xxxxxxxxxxxxx>
Date: Mon, 02 Mar 2009 18:58:31 +0800

Matthew Dillon wrote:

*snip*


The boot1 code was using an 8086 copy loop to copy the boot2 code to its target origin. I don't see how it could possibly have EVER worked properly for any boot2 code over 16K due to a 64K wrap off the end of the 8086 segment. And yet, it seemed to, so I am somewhat at a loss.

*...a few lines later*



    disklabel32 is still restricted to an 8K boot2 and there is nothing
    we can do about that.

If legacy boot2 couldn't grow beyond 8K, (or 16K) neither a 32K nor 64K wrap would have mattered?


And one can put a reasonably useful 16-bit Virtual Machine OS, Virtual Memory System, with disk I/O and an editor into 8K. Even on an 8-bit CPU. Forth and ASM didn't go away. They just hide really well....

;-)

-Bill



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