Date: Tue, 16 Mar 1999 11:52:20 -0700 From: Nate Williams <nate@mt.sri.com> To: SHUDO Kazuyuki <shudoh@muraoka.info.waseda.ac.jp> Cc: Nate Williams <nate@mt.sri.com>, freebsd-java@FreeBSD.ORG Subject: Re: jre1.1.7 core dump on FreeBSD 3.1 (intel) Message-ID: <199903161852.LAA05728@mt.sri.com> In-Reply-To: <199903110420.NAA03845@cafe.muraoka.info.waseda.ac.jp> References: <199903110107.SAA12226@mt.sri.com> <199903110420.NAA03845@cafe.muraoka.info.waseda.ac.jp>
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> FreeBSD don't mask some floating point exceptions which
> are masked on initial state of x87. Overflow(OM),
> Devided by zero(ZM) and illegal operation(IM) aren't
> masked.
>
> Does JDK for FreeBSD change these FPU exception masks
> from default value?
>
> We can investigate the states of the masks by the
> following code:
>
> #include <stdio.h>
> int main(int argc, char **argv) {
> unsigned short cw;
> __asm__("fnstcw %0" : "=m"(cw));
> printf("FPU control word: 0x%04x\n", (int)cw);
> return 0;
> }
>
> The code shows FPU control word.
> On linux: 0x037f
> On FreeBSD: 0x1272
For what it's worth (this jumped out while I was working on Steve
Price's ELF patches to JDK1.1.7), the FPU mask in the JDK is set to
0x127f. (See javasrc/src/freebsd/java/green_threads/src/context.c).
I'm not sure what Linux uses, but it may be similar.
Nate
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