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Re: quick question on 64-bit values with 32-bit inline assembly

To: "M. Warner Losh" <imp@bsdimp.com>
Subject: Re: quick question on 64-bit values with 32-bit inline assembly
From: "Maciej W. Rozycki" <macro@linux-mips.org>
Date: Tue, 29 Jan 2008 10:16:38 +0000 (GMT)
Cc: ralf@linux-mips.org, cfriesen@nortel.com, linux-mips@linux-mips.org
In-reply-to: <20080128.142610.1159133450.imp@bsdimp.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20080122200751.GA2672@linux-mips.org> <20080128.140245.-108809632.imp@bsdimp.com> <20080128211803.GA20434@linux-mips.org> <20080128.142610.1159133450.imp@bsdimp.com>
Sender: linux-mips-bounce@linux-mips.org
On Mon, 28 Jan 2008, M. Warner Losh wrote:

> : The architecture manual doesn't make a difference between 32-bit and
> : 64-bit for rdhwr.  My reading is the entire 64-bit would have to be
> : transfered.
> 
> Hmmm, the manual I have specifically calls out the difference...

 Concerning implementation-specific registers number 30 and 31 the MIPS64 
architecture manual states that if the register in question is 64-bit and 
64-bit operations are enabled then it is copied as is and otherwise it is 
sign-extended from the bit #31.  Note that the kernel mode implies 64-bit 
operations enabled.

  Maciej

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