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From: culberts@hplwbc.hpl.hp.com (Bruce Culbertson)
Newsgroups: comp.sys.nsc.32k
Subject: Re: Bug in minix library setjmp.s; lots of GNU tools diffs available
Message-ID: <9102081832.AA02175@hplwbc.hpl.hp.com>
Date: 8 Feb 91 18:32:17 GMT
Sender: news@daver.bungi.com
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Approved: news@daver.bungi.com

> Jyrki Kuoppala (jkp) writes:

> When porting emacs to pc532-Minix, I noticed there's a bug in the
> setjmp library routine - it doesn't save registers r3-r7 (and f4-f7)
> which I think it should do.  This seems like a serious bug and I'm
> surprised it has caused so little trouble when compiling all the other
> software I have on the pc532.

I have read the various man pages for BSD, SysV, etc. and I think my
setjmp/longjmp actually conforms to the functionality it is required to
support.  However, I agree with Jyrki completely -- many programs we all
know and love incorrectly expect more from setjmp/longjmp and it is a
real pain if setjmp/longjmp does not preserve as much of the environment
as possible.  I have already made similar changes to the setjmp/longjmp
in the soon-to-be released 1.3/1.5 hybrid pc532-Minix.

> I now have a complete environment (including libc) working with the
> GNU tools: gcc 1.39 with patches, gas 1.38.1 with patches, GNU
> binutils with patches, GNU make 3.59, emacs 18.57 (subprocesses don't
> work yet), bash 1.05.1, GNU fileutils etc. ...

Great!  This is a really nice contribution.

> Bootstrapping with the broken Minix programs was also painful.

May I request that people not make vague negative comments like this.
What features of what programs are broken?  An OS and C implementation
are not broken just because they cannot compile and support all the
GNU programs.  I will attempt to fix bugs if I know what they are.

> 	addr	0(f4),sj_f4(r0)	#save f4
>	addr	0(f5),sj_f5(r0)	#save f5
>	addr	0(f6),sj_f6(r0)	#save f6
>	addr	0(f7),sj_f7(r0)	#save f7

I these are illegal instructions.  If you look at the instruction
encoding, you will see that there is no way to specify an addressing
mode like "0(f4)".  If gas does not catch this, it probably encodes
it as "0(r4)", which is not what you want.  The following should work:

 	movf	f4,sj_f4(r0)	#save f4
	movf	f5,sj_f5(r0)	#save f5
	movf	f6,sj_f6(r0)	#save f6
	movf	f7,sj_f7(r0)	#save f7

Cheers,
Bruce Culbertson