On Fri, Aug 24, 2018 at 05:18:45PM +0800, peng.hao2@xxxxxxxxxx wrote:
[...]
> > > - cpu_physical_memory_write(ent->phys_addr, ent->data, ent->len);
> > > + if (ent->pio == 1) {
> > > + address_space_rw(&address_space_io, ent->phys_addr,
> > > + MEMTXATTRS_NONE, ent->data, ent->len, true);
>
> > Why exactly MEMTXATTRS_NONE is the right attrs argument here?
> > Why MEMTXATTRS_UNSPECIFIED wouldn't work?
>
> I didn't notice MEMTXATTRS_NONE is the same as MEMTXATTRS_UNSPECIFIED.
> MEMTXATTRS_NONE is redundant.
They are not exactly the same (see below), but in either case I'm
not sure it would make any difference for PIO.
> >> + } else {
> >> + cpu_physical_memory_write(ent->phys_addr, ent->data, ent->len);
> >> + }
> >> smp_wmb();
> >> ring->first = (ring->first + 1) % KVM_COALESCED_MMIO_MAX;
> >> }
> >> diff --git a/include/exec/memattrs.h b/include/exec/memattrs.h
> >> index d4a1642..12fd64f 100644
> >> --- a/include/exec/memattrs.h
> >> +++ b/include/exec/memattrs.h
> >> @@ -45,7 +45,7 @@ typedef struct MemTxAttrs {
> >> * from "didn't specify" if necessary).
> >> */
> >> #define MEMTXATTRS_UNSPECIFIED ((MemTxAttrs) { .unspecified = 1 })
> >> -
> >> +#define MEMTXATTRS_NONE ((MemTxAttrs) { 0 })
--
Eduardo
