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    SubjectRe: [RFT] Port 0x80 I/O speed
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    On 12-12-07 06:23, Kyle McMartin wrote:

    > On Wed, Dec 12, 2007 at 12:31:18AM +0100, Rene Herman wrote:
    >> asm volatile ("rdtsc": "=A" (tsc));
    >
    > rdtsc returns a 64-bit value in two 32-bit regs, you need to do
    >
    > inline unsigned long long rdtsc(void)
    > {
    > unsigned int lo, hi;
    > asm volatile ("rdtsc": "=a" (lo), "=d" (hi));
    > return (unsigned long long)hi << 32 | lo;
    > }
    >
    > as in msr.h, otherwise you'll only be looking at the value in %rax.

    On 32-bit, "=A" is edx:eax. Not sure what the point is in not letting it be
    that on 64-bit in fact, but yes, the thing should be compiled as 32-bit.

    Rene.


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