debugging macros D/RD/ND
interrupt mitigation for e1000
paravirtualized e1000
add files from FreeBSD
RATE monitor added
tried to implement exit protocol
csb exit protocol: qemu_bh_cancel
e1000: CSB acquire/release protocol revised

When writing CSBAH/CSBAL registers, the guest is always required to
write CSBAL last. When this happens, the host unmaps (releases) the
previously mapped CSB, if any. In the last case it also cancels the
tx_bh scheduling, so that no invalid CSB access can be done.

After that, if the new CSBAL/CSBAH content specifies a non-zero
physical address, the host maps (acquires) the new CSB.

==============================================================

The initialization of s->tx_count has been moved from start_xmit() to
e1000_tx_bh(), in order to avoid BH spinning in case the TX operation
is disabled in hardware with the TCTL register (see the if statement
at the beginning of start_xmit()).
e1000_csb definition moved into net/paravirt.h
netmap support
added missing case for -netdev option
added devname= option to -netdev netmap

This is used to specify a device name different from
/dev/netmap.

The previous solution used 'name' for this, but 'name'
is better used as an identifier for the netdev.
rtl8139cp: paravirtualization init

Paravirtualization support detection -- OK
CSB acquire/release protocol         -- OK
rtl8139cp: paravirt --> host_isr
fix compilation on 32 bit systems
rtl8139cp: tx_bh first implementation

Race avoidance is still missing!!
rtl8139cp: guest_need_?xkick filter implemented
rtl8139cp: Exit from BH with race avoidance

The race between guest pushing another TX descriptor in the ring (checking
whether it has to write to TxPoll) and the host raising csb->host_need_txkick
is avoided by double checking the next TX descriptor ownership flag after
csb->host_need_txkick has been raised.

The missing qemu_bh_cancel() has been added to the release protocol.

Straightforward optimization in the TX path: Only one pci_dma_read() when
reading the next TxDescriptor instead of four of them (one for each
descriptor word).
rtl8139cp: RATE monitor added
rtl8139cp: guest_need_?xkick filter fixed

We don't consider at all IntrMask when delivering an
interrupt in paravirtual mode.