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

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

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++;

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel