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From: Hugh Graham <hugh@openbsd.org>
Date: Sun, 15 Jul 2001 02:53:23 -0700
To: Lord Isildur <mrfusion@umbar.vaxpower.org>
Cc: port-vax@netbsd.org
Subject: Re: broken KA690?
Message-ID: <20010715025323.A27037@argus.oxide.org>
References: <200107141540.f6EFel000342@unixag-kl.fh-kl.de> <Pine.3.89.10107150350.B4021-0100000@umbar.vaxpower.org>
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In-Reply-To: <Pine.3.89.10107150350.B4021-0100000@umbar.vaxpower.org>; from mrfusion@umbar.vaxpower.org on Sun, Jul 15, 2001 at 04:39:00AM -0400

On Sun, Jul 15, 2001 at 04:39:00AM -0400, Lord Isildur wrote:
> 
> hmm, i am wondering if i don't have a broken KA690: 
> i have discovered that i am getting reserved instruction faults 
> when trying to execute the emodd instruction (a D_floating instruction)
> which _should_ be supported by the NVAX! (this instruction is used by
> a call in stdio that in turn is used in doprnt , in turn used by printf)
> 
Your machine's not broken. I've not got a reference for which
instructions are available on which cpu families, but I've never seen
EMODD work natively on NVAX.  The confusion stems probably from so
much old code assuming these instructions will be present.

> it's totally reproducible, too, if i try to run a d_floating instruction, 
> i get the reserved operand exception instead of the thing actually
> running. Is there some kind of status bit or something that needs to
> be frobbed? as far as i remember, it worked fine under vms. 

VMS (and ultrix) have a complete emulation for these instructions.
Ragge and BJC have made a start with a partial POLYD and full EMODD,
but writing a complete emulation isn't a trivial project.

> (worse, i forgot the system passwd, and the instructions to get in around 
> that dont seem to work either.. this is vms 7.2 though so maybe the uvax 
> faq's method doesnt apply to 7.2) 
> 
> anyway, if anybody has and idea whats up with this board getting such 
> faults on such normal instructions, is it hosed?
> 

See if your quantity is small enough you can get away with a CVTDL,
CVTLD, SUBD3 sequence instead of an EMODD.

/Hugh

> isildur