rombios/ata: Reading this status register has no relevant side effects
authorAndrew Cooper <andrew.cooper3@citrix.com>
Tue, 6 Aug 2013 13:48:38 +0000 (14:48 +0100)
committerIan Campbell <ian.campbell@citrix.com>
Thu, 8 Aug 2013 11:03:16 +0000 (12:03 +0100)
So taking two traps when one will do is pointless.  This removes 1 of 13
VMExits on the int 0x13 hotpath.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Keir Fraser <keir@xen.org>
tools/firmware/rombios/rombios.c

index a3efc618e0aa693661f4e1097c03f3e6013809f4..f5557477a5aeb87d88d46b314fd6d13e75af6292 100644 (file)
@@ -2540,7 +2540,6 @@ static int await_ide(when_done,base,timeout)
   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++;