From: "Quim K Holland" <qkholland@my-deja.com>
To: dledford@redhat.com
Cc: hpa@zytor.com, linux-kernel@vger.kernel.org
Subject: Re: cpu_has_fxsr or cpu_has_xmm?
Date: Fri, 23 Feb 2001 12:51:05 -0800 [thread overview]
Message-ID: <200102232051.MAA18803@mail17.bigmailbox.com> (raw)
>>>>> "DL" == Doug Ledford <dledford@redhat.com> writes:
>> > --- linux.vanilla/arch/i386/kernel/i387.c Thu Feb 22 09:05:35 2001
>> > +++ linux.ac/arch/i386/kernel/i387.c Sun Feb 4 10:58:36 2001
>> > @@ -179,7 +179,7 @@
>> >
>> > unsigned short get_fpu_mxcsr( struct task_struct *tsk )
>> > {
>> > - if ( cpu_has_fxsr ) {
>> > + if ( cpu_has_xmm ) {
>> > return tsk->thread.i387.fxsave.mxcsr;
>> > } else {
>> > return 0x1f80;
>> >
DL> As to the correctness, the mxcsr register really only exists
DL> if you have xmm, so the xmm is the correct test. However,...
DL> ... User space programmers should be checking for xmm
DL> capability themselves before ever paying attention to mxcsr
DL> anyway, so it's not an end of the world error.
If that is the case, wouldn't it be simpler to always return
tsk->thread.i387.fxsave.mxcsr from this function, and initialize
that field to 0x1f80 (whatever that magic number means) when
the structure is built?
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next reply other threads:[~2001-02-23 20:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-02-23 20:51 Quim K Holland [this message]
2001-02-23 21:44 ` cpu_has_fxsr or cpu_has_xmm? H. Peter Anvin
-- strict thread matches above, loose matches on Subject: below --
2001-02-23 5:38 Quim K Holland
2001-02-23 6:11 ` H. Peter Anvin
2001-02-23 11:23 ` Doug Ledford
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