GEMs is unable to discriminate UDP from TCP packets such that
it can generate 0x0000 checksum value for the UDP datagram. So the
UDP checksum offload was disabled by default. You can enable it
by setting link0 flag with ifconfig(8).
o bus_dma(9) clean up. It now correctly set number of required DMA
segments/size and removed incorrect use of BUS_DMA_ALLOCNOW flag
in static allocations done via bus_dmamem_alloc(9).
o Implemented ALTQ(9) support.
o Implemented Tx side bus_dmamap_load_mbuf_sg(9) which can remove
several book keeping chores orginated from call-back mechanism.
Therefore gem_txdma_callback() was removed and its functionality
was reimplemented in gem_load_txmbuf().
o Don't set GEM_TD_START_OF_PACKET flag until all remaining mbuf
chains are set. I think it was a long standing bug and it caused
fluctuating interrupts/CPU usage patterns while netperf test
is in progress. Previously it seems that we race with the device.
Because I don't have a documentation for GEM I'm not sure this is
correct but almost all other documentations I have stated this
implications on setting SOP mark in descriptor ring(e.g. hme(4)).
o Borrowed gem_defrag() from ath(4) which is supposed to be much
faster than m_defrag(9) since it's not need to defrag all
mbuf chains.
o gem_load_txmbuf() was changed to allow passed mbuf chains to free.
Caller of gem_load_txmbuf() correctly handles freed mbuf chains.
o In gem_start_locked(), added checks for availability of Tx
descriptors before trying to load DMA maps which could save CPU
cycles when number of available descriptors are low. Also, simplyfy
IFF_DRV_OACTIVE detection logic.
o Removed hard-coded function names in CTR macros and replaced it
with __func__.
o Moved statistics counter register access to gem_tick() to reduce
number of PCI bus accesses. There is no reason to update statistics
counters in interrupt handler.
o Removed unnecessary call of gem_start_locked() in gem_ioctl().
Reviewed by: grehan (initial version), marius (with improvements and suggestions)
Tested by: grehan (ppc), marius(sparc64)
12fb0330d8