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[/] [openrisc/] [trunk/] [or_debug_proxy/] [README] - Diff between revs 46 and 47

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Rev 46 Rev 47
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0.1.0 090201 jb@orsoc.se
0.1.0 090201 jb@orsoc.se
0.1.1 090304 jb@orsoc.se
0.1.1 090304 jb@orsoc.se
0.1.2 090511 jb@orsoc.se
0.1.2 090511 jb@orsoc.se
0.1.3 090604 jb@orsoc.se
0.1.3 090604 jb@orsoc.se
0.1.4 090828 jb@orsoc.se
0.1.4 090828 jb@orsoc.se
 
0.1.5 090903 jb@orsoc.se
===============================================================================
===============================================================================
-- Installation --
-- Installation --
===============================================================================
===============================================================================
 
 
The OR debug proxy application runs on multiple platforms only requiring
The OR debug proxy application runs on multiple platforms only requiring
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       noticing that, over a 4-odd megabyte transfer from GDB, taking about 4
       noticing that, over a 4-odd megabyte transfer from GDB, taking about 4
       minutes, the proxy only executed for 2.5 seconds, and the three most
       minutes, the proxy only executed for 2.5 seconds, and the three most
       used functions, accounting for 50% of execution were functions in the
       used functions, accounting for 50% of execution were functions in the
       driver. This indicates that either better use of, or better
       driver. This indicates that either better use of, or better
       implementation of, the driver could dramatically increase speed.
       implementation of, the driver could dramatically increase speed.
 
       SOLVED: It appears increasing the packet size of the GDB transfers can
 
       achieve a significant increase in speed. GDB queries the proxy at when
 
       it connects about its maximum packet size. It was previously 255 bytes
 
       and this meant larger downloads were "slow". Raising this transfer size
 
       to around 4kB (4096 bytes) resulted in a throughput increase of almost
 
       10-times. This is due to the fact that most of the transfer time is
 
       spent on waiting for the driver - the overhead per call is significant
 
       if only transferring 255 bytes, so increasing the amount per transfer
 
       reduces the amount of time waiting for the driver to perform the trans-
 
       action. Sizes greater than 4kB, for some reason, cause the driver to
 
       have issues - resulting in incorrect CRC reading and bad Status returns
 
       from the driver functions. Why this is so should be investigated.
     * USB<->JTAG Driver TODO:
     * USB<->JTAG Driver TODO:
       Get the latest version of the MPSSE function code (from
       Get the latest version of the MPSSE function code (from
       http://ftdichip.com/Projects/MPSSE/FTCJTAG/FTCJTAG_Source.zip at last
       http://ftdichip.com/Projects/MPSSE/FTCJTAG/FTCJTAG_Source.zip at last
       check) and update our Linux compatible version with the ones here. This
       check) and update our Linux compatible version with the ones here. This
       might provide improved stability or performance, but from the list of
       might provide improved stability or performance, but from the list of

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