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From: "Maciej W. Rozycki" <macro@linux-mips.org>
To: Ralf Baechle <ralf@linux-mips.org>
Cc: Jayachandran C <jchandra@broadcom.com>, linux-mips@linux-mips.org
Subject: Re: [PATCH UPDATED 4/4] MIPS: Move definition of SMP processor id register to header file
Date: Thu, 20 Jun 2013 16:40:59 +0100 (BST)	[thread overview]
Message-ID: <alpine.LFD.2.03.1306201630180.29828@linux-mips.org> (raw)
In-Reply-To: <20130620144821.GB30061@linux-mips.org>

On Thu, 20 Jun 2013, Ralf Baechle wrote:

> So I've removed it again for now.
> 
> Maciej, I wonder why does gas in MIPS III/IV mode accept
> 
> 	dmfc0	$reg1, $cp0reg
> 
> but not
> 
> 	dmfc0	$reg1, $cp0reg, 0
> 
> The generated code is the same after all.  Same for MIPS I/II mode and 
> mfc0.

 The <sel> operand and instruction field was only added to these 
instructions with the MIPS64 ISA (MIPS32 ISA for MFC0/MTC0).  Previously 
processors did not decode this field and consequently the assembler 
notation only supports two operands.

 Since AFAICT the offending pieces are macros I suggest simply dumping the 
redundant ", 0" part, the two-argument form is as you've observed 
equivalent.

  Maciej

  reply	other threads:[~2013-06-20 15:41 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-11 15:41 [PATCH 0/4] Use scratch registers on XLR/XLS/XLP Jayachandran C
2013-06-11 15:41 ` [PATCH 1/4] MIPS: Allow platform specific scratch registers Jayachandran C
2013-06-11 15:41 ` [PATCH 2/4] MIPS: Fixup check for invalid scratch register Jayachandran C
2013-06-11 15:41 ` [PATCH 3/4] MIPS: mm: Use scratch for PGD when !CONFIG_MIPS_PGD_C0_CONTEXT Jayachandran C
2013-06-18 12:45   ` [PATCH UPDATED " Jayachandran C
2013-06-18 12:45     ` [PATCH UPDATED 4/4] MIPS: Move definition of SMP processor id register to header file Jayachandran C
2013-06-20 14:48       ` Ralf Baechle
2013-06-20 15:40         ` Maciej W. Rozycki [this message]
2013-06-20 15:19     ` [PATCH UPDATED 3/4] MIPS: mm: Use scratch for PGD when !CONFIG_MIPS_PGD_C0_CONTEXT Ralf Baechle
2013-06-11 15:41 ` [PATCH 4/4] MIPS: Move definition of SMP processor id register to header file Jayachandran C

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