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From: kato@eclogite.eps.nagoya-u.ac.jp (KATO Takenori)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Cyrix 387 error reporting broken
Date: 9 Dec 1996 03:58:29 GMT
Organization: Earth Planet. Sci., Nagoya Univ.
Lines: 46
Message-ID: <58g2p5$9a4@news.cc.nagoya-u.ac.jp>
References: <58cd6g$c9m@soda.CSUA.Berkeley.EDU>
NNTP-Posting-Host: marble.eps.nagoya-u.ac.jp
Mime-Version: 1.0
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X-Newsreader: mnews [version 1.19PL2] 1996-01/26(Fri)
In article <58cd6g$c9m@soda.CSUA.Berkeley.EDU>
<mconst@soda.CSUA.Berkeley.EDU>wrote:
>
> npx0: error reporting broken; using 387 emulator
>
> The emulator works fine, but I'm curious if this is some known bug with
> older-revision 387s. I didn't see any mention in npx.c of a known bug,
> and in fact it mentions that the npx code was tested on a Cyrix 387 (and
> presumably worked).
This happens also on some Cyrix 486 box and Cyrix 5x86 with `faster
fpu exception' flag (undocumented).
Please try a patch bellow. The patch is produced from npx.c in
FreeBSD 2.1.5 RELEASE.
---------- BEGIN ----------
*** npx.c.orig Mon Dec 9 12:52:32 1996
--- npx.c Mon Dec 9 12:53:20 1996
***************
*** 290,295 ****
--- 290,304 ----
*/
control &= ~(1 << 2); /* enable divide by 0 trap */
fldcw(&control);
+ #ifdef FPU_ERROR_BROKEN
+ /*
+ * FPU error signal doesn't work on some CPU
+ * accelerator board.
+ */
+ npx_ex16 = 1;
+ dvp->id_irq = 0;
+ return (-1);
+ #endif
npx_traps_while_probing = npx_intrs_while_probing = 0;
fp_divide_by_0();
if (npx_traps_while_probing != 0) {
---------- END ----------
----
KATO Takenori <kato@eclogite.eps.nagoya-u.ac.jp>
Dept. Earth Planet. Sci., Nagoya Univ., Nagoya, 464-01, Japan
PGP public key: finger kato@eclogite.eps.nagoya-u.ac.jp