Re: e1000 PXE breakage bisected down in kvm-userspace

[Charles Duffy <Charles_Duffy@messageone.com>]

Anthony Liguori wrote:
> diff --git a/qemu/hw/e1000.c b/qemu/hw/e1000.c
> index 1be69ec..6a07b0c 100644
> --- a/qemu/hw/e1000.c
> +++ b/qemu/hw/e1000.c
> @@ -521,8 +521,8 @@ e1000_can_receive(void *opaque)
> {
>     E1000State *s = opaque;
> 
> -    return ((s->mac_reg[RCTL] & E1000_RCTL_EN) &&
> -           s->mac_reg[RDH] != s->mac_reg[RDT]);
> +    return (!(s->mac_reg[RCTL] & E1000_RCTL_EN) ||
> +            s->mac_reg[RDH] != s->mac_reg[RDT]);
> }

Having e1000_can_receive return true only if s->mac_reg[RDH] != 
s->mac_reg[RDT] means that the logic in e1000_receive() which sets the 
receive overflow flag is never reached.

I think it may be more correct to check only for s->mac_reg[RCTL] & 
E1000_RCTL_EN.