From: Ralf Baechle <ralf@oss.sgi.com>
To: Atsushi Nemoto <nemoto@toshiba-tops.co.jp>
Cc: linux-mips@oss.sgi.com
Subject: Re: NON FPU cpus (again)
Date: Thu, 20 Sep 2001 05:16:43 +0200 [thread overview]
Message-ID: <20010920051642.C11714@dea.linux-mips.net> (raw)
In-Reply-To: <20010920.121316.74756227.nemoto@toshiba-tops.co.jp>; from nemoto@toshiba-tops.co.jp on Thu, Sep 20, 2001 at 12:13:16PM +0900
On Thu, Sep 20, 2001 at 12:13:16PM +0900, Atsushi Nemoto wrote:
> Following codes in exit_thread() and flush_thread() should be executed
> only if (mips_cpu.options & MIPS_CPU_FPU) == 0, shouldn't it?
>
> set_cp0_status(ST0_CU1);
> __asm__ __volatile__("cfc1\t$0,$31");
>
> BTW, I can not see any point in copying FCR31 to r0. What is a
> purpose of the cfc1 instruction?
On CPUs with imprecise exceptions a FPU exception might still be pending
and possibly be taken arbitrarily delayed. The cfc1 instruction serves
as an exception barrier for such exceptions. At this time TFP is the
only CPU which features imprecise exceptions.
Ralf
next prev parent reply other threads:[~2001-09-20 3:17 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-02-07 13:48 NON FPU cpus - way to go Florian Lohoff
2001-02-07 16:36 ` Maciej W. Rozycki
2001-02-07 16:59 ` Florian Lohoff
2001-02-07 18:19 ` Maciej W. Rozycki
2001-02-07 18:53 ` Alan Cox
2001-02-07 18:53 ` Alan Cox
2001-02-07 19:37 ` Jun Sun
2001-02-07 20:43 ` Joe deBlaquiere
2001-02-08 8:45 ` Geert Uytterhoeven
2001-02-08 10:13 ` Maciej W. Rozycki
2001-02-08 10:52 ` Kevin D. Kissell
2001-02-08 10:52 ` Kevin D. Kissell
2001-02-08 11:19 ` Maciej W. Rozycki
2001-02-08 11:38 ` Kevin D. Kissell
2001-02-08 11:38 ` Kevin D. Kissell
2001-02-08 12:05 ` Maciej W. Rozycki
2001-02-08 10:42 ` Maciej W. Rozycki
2001-02-08 10:53 ` Geert Uytterhoeven
2001-02-08 10:58 ` Alan Cox
2001-02-08 10:58 ` Alan Cox
2001-02-08 11:05 ` Geert Uytterhoeven
2001-02-08 11:22 ` Maciej W. Rozycki
2001-02-07 19:01 ` Jun Sun
2001-02-07 22:51 ` Kevin D. Kissell
2001-02-07 22:51 ` Kevin D. Kissell
2001-02-08 10:54 ` Maciej W. Rozycki
2001-02-08 10:24 ` Maciej W. Rozycki
2001-09-20 3:13 ` NON FPU cpus (again) Atsushi Nemoto
2001-09-20 3:16 ` Ralf Baechle [this message]
2001-09-20 4:02 ` Atsushi Nemoto
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