On Mon, 30 Apr 2007 12:51:05 +0200, Juergen Beisert wrote: > setCx86(CX86_CCR2, getCx86(CX86_CCR2) | 0x88); > > If this register is 0x00 before, it is still 0x00 after this line. If I > change > the line into this: > > ccr2 = getCx86(CX86_CCR2); > ccr2 |= 0x88; > setCx86(CX86_CCR2, ccr2); > > register ccr2 is 0x88 after the setCx86 call and the power saving feature is > active (and BTW: the TSC is useless then, because it also stops when the CPU > runs into a HLT instruction). > > setCx86 and getCx86 are macros defined in include/asm-i386/processor.h: > > #define getCx86(reg) ({ outb((reg), 0x22); inb(0x23); }) > > #define setCx86(reg, data) do { \ > outb((reg), 0x22); \ > outb((data), 0x23); \ > } while (0) > > Maybe the compiler does the wrong thing if someone uses these macros in the > same instruction?
The compiler is fine, it's the setCx86() macro that is utter crap because it fails to behave like a function by not evaluating its arguments before performing its outb() statements. Converting them to static inlines would be the best solution. Something like static inline u8 getCx86(unsigned int reg) { outb(reg, 0x22); return inb(0x23); } static inline void setCx86(unsigned int reg, u8 data) { outb(reg, 0x22); outb(data, 0x23); } ought to work. /Mikael - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/