Re: [Xen-devel] [PATCH 3 of 5] rombios/ata: Reading this status register has no relevant side effects

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

No relevant side effects according to some spec or according to the
current qemu implementation?

Does it have any "irrelevant" side effects?

On Mon, 2012-11-26 at 16:41 +0000, Andrew Cooper wrote:
> So taking two traps when one will do is pointless.  This codepath is on the 
> int
> 0x13 hot path, and removing it has about a 30% reduction in the number of 
> traps
> to Qemu during Win7 boot.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> 
> diff -r c223c044afbf -r a8645d836a0e tools/firmware/rombios/rombios.c
> --- a/tools/firmware/rombios/rombios.c
> +++ b/tools/firmware/rombios/rombios.c
> @@ -2540,7 +2540,6 @@ static int await_ide(when_done,base,time
>    Bit32u time=0,last=0;
>    Bit16u status;
>    Bit8u result;
> -  status = inb(base + ATA_CB_STAT); // for the times you're supposed to 
> throw one away
>    for(;;) {
>      status = inb(base+ATA_CB_STAT);
>      time++;
> 
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> http://lists.xen.org/xen-devel



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