On 09/18/2012 10:21 AM, Xiao Guangrong wrote: > On 09/16/2012 08:07 PM, Avi Kivity wrote: > >> + /* >> + * On a write fault, fold the dirty bit into accessed_dirty by shifting it one >> + * place right. >> + * >> + * On a read fault, do nothing. >> + */ >> + accessed_dirty &= pte >> (write_fault >> ilog2(PFERR_WRITE_MASK)); > > It is too trick: it depends on DIRTY_SHIFT = ACCESSED_SHIFT + 1. How about change it > to: > accessed_dirty &= pte >> (!!write_fault >> (DIRTY_SHIFT - ACCESSED_SHIFT)) ? !! forces a branch, unless gcc is really clever. So I changed it to shift = write_fault >> ilog2(PFERR_WRITE_MASK); shift *= PT_DIRTY_SHIFT - PT_ACCESSED_SHIFT; accessed_dirty &= pte >> shift; which should result in the same code. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
