Re: [Qemu-devel] [PATCH] only check RCTL_EN in e1000_can_receive()

[Anthony Liguori]

Charles Duffy wrote:
> e1000_receive() has code to raise a receive overflow interrupt when 
> the receive buffer head and tail match. However, with the present 
> implementation of e1000_can_receive(), this code is unreachable -- and 
> etherboot breaks as a result.
>
> The attached quick-and-dirty patch fixes etherboot for e1000, and does 
> not appear to break post-boot functionality.

While this is a legitimate bug, it's probably only present in KVM or 
when using the slirp rate limiting.  Right in QEMU, a can_receive 
handler for a network card is largely ignored whereas in KVM, it is used 
to throttle receive for the tap device.

Nonetheless, the correct behaviour is to raise an interrupt when a 
packet could be received but no buffers are available so I've applied 
this patch.  Thanks.

Regards,

Anthony Liguori