linux-kernel - Re: [PATCH] [9/11] x86: Replace NSC/Cyrix specific chipset access macros by inlined functions.

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Message-Id: <200707221245.27778.juergen127@kreuzholzen.de>
Date:	Sun, 22 Jul 2007 12:45:26 +0200
From:	Juergen Beisert <juergen127@...uzholzen.de>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	Andi Kleen <ak@...e.de>, patches@...-64.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [9/11] x86: Replace NSC/Cyrix specific chipset access macros by inlined functions.

On Saturday 21 July 2007 14:00, Alexey Dobriyan wrote:
> On Fri, Jul 20, 2007 at 05:32:53PM +0200, Andi Kleen wrote:
> > --- /dev/null
> > +++ linux/include/asm-i386/processor-cyrix.h
> > @@ -0,0 +1,30 @@
> > +/*
> > + * NSC/Cyrix CPU indexed register access. Must be inlined instead of
> > + * macros to ensure correct access ordering
> > + * Access order is always 0x22 (=offset), 0x23 (=value)
> > + *
> > + * When using the old macros a line like
> > + *   setCx86(CX86_CCR2, getCx86(CX86_CCR2) | 0x88);
> > + * gets expanded to:
> > + *  do {
> > + *    outb((CX86_CCR2), 0x22);
> > + *    outb((({
> > + *        outb((CX86_CCR2), 0x22);
> > + *        inb(0x23);
> > + *    }) | 0x88), 0x23);
> > + *  } while (0);
> > + *
> > + * which in fact violates the access order (= 0x22, 0x22, 0x23, 0x23).
> > + */
> > +
> > +static inline u8 getCx86(u8 reg)
> > +{
> > +	outb(reg, 0x22);
> > +	return inb(0x23);
> > +}
> > +
> > +static inline void setCx86(u8 reg, u8 data)
> > +{
> > +	outb(reg, 0x22);
> > +	outb(data, 0x23);
> > +}
>
> Why bother with new header, just make static inline in asm/processor.h.

Already tried. But it requires asm/io.h everywhere, because it contains 
inb/outb. When they where macros that doesn't matter. Just included asm/io.h 
when these macros where used. But as inlined functions you need asm/io.h all 
the time.

Juergen
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