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Date:      Fri, 15 Nov 1996 00:15:37 -0800
From:      "Jordan K. Hubbard" <jkh@time.cdrom.com>
To:        Bruce Evans <bde@zeta.org.au>
Cc:        cvs-all@freefall.freebsd.org, CVS-committers@freefall.freebsd.org, cvs-sys@freefall.freebsd.org, jkh@freefall.freebsd.org
Subject:   Re: cvs commit: src/sys/i386/i386 locore.s 
Message-ID:  <11301.848045737@time.cdrom.com>
In-Reply-To: Your message of "Fri, 15 Nov 1996 18:37:48 %2B1100." <199611150737.SAA03853@godzilla.zeta.org.au> 

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> >  Modified:    sys/i386/i386  locore.s
> >  Log:
> >  movl instruction should have been lea (this is why userconfig didn't
> >  work in 2.1).
> 
> Erm, the movl looks OK to me, and the lea isn't an i386 instruction so
> it doesn't compile.

[scratches his head]

Why did this compile for me?  And why did that single fix (suggested
by Don Lewis, BTW, who knows far more about the x86 instruction set
than I) result in USERCONFIG_BOOT working where it did not before?
Perhaps this was something which should have stayed out of 2.2 and
remained confined to 2.1.6 due to differences in the compiler tech?

After all the shenatigans of the last week, you can bet that I tested
this very very carefully with a before-and-after check of just that
one line changed, and the movl version blows up under 2.6.3 whereas
the lea version works fine - I'm actually booting 2.1.6 floppies now
where I never could before.

I'm not saying you're wrong, since what I know about x86 assembly
could fit into a thimble (the only instruction set I ever learned
backwards and forwards was the for the NS32K architecture, and it
spoiled me for other processor architectures), I'm simply saying that
the empirical evidence runs very much counter to what you're saying.

Any theories?

					Jordan



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