On Thu, Dec 18, 2014 at 12:01:48AM -0500, Jason Wang wrote: > > > ----- Original Message ----- > > Some drivers set RDT=RDH. Oddly, this works on real hardware. To work > > around this, autodecrement RDT when this happens. > > > > Signed-off-by: Richard Tollerton <rich.toller...@ni.com> > > Signed-off-by: Jeff Westfahl <jeff.westf...@ni.com> > > --- > > hw/net/e1000.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > Please describe more details on the issue. > > The spec 3.2.6 said: > > " > When the head pointer is equal to the tail pointer, the ring is empty. > " > > So RDT=RDH in fact empty the ring. No?
Richard, can you respond please? I'd like to see this clarified in code comment or commit message before applying this patchset. > > > > diff --git a/hw/net/e1000.c b/hw/net/e1000.c > > index 44ae3a8..b8cbfc1 100644 > > --- a/hw/net/e1000.c > > +++ b/hw/net/e1000.c > > @@ -1152,6 +1152,12 @@ mac_writereg(E1000State *s, int index, uint32_t val) > > static void > > set_rdt(E1000State *s, int index, uint32_t val) > > { > > + if (val == s->mac_reg[RDH]) { /* Decrement RDT if it's too big */ > > + if (val == 0) { > > + val = s->mac_reg[RDLEN] / sizeof(struct e1000_rx_desc); > > + } > > + val--; > > + } > > s->mac_reg[index] = val & 0xffff; > > if (e1000_has_rxbufs(s, 1)) { > > qemu_flush_queued_packets(qemu_get_queue(s->nic)); > > -- > > 2.1.3 > > > > > >