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Re: [partial-reconfig] Partially reconfiguring a readback bitstream
Hello Enno,
I also research the saving and restoring of the hardware task. There are three papers about this: "context saving and restoring for multitasking in reconfigurable systems","multitasking on fpga coprocessors","preemptive multitasking on fpgas".
The readback bitstream contains the configuration and the status of the register or ram. If we want to realize the saving and restoring of the hardware task, We must use the status instead of the configuration.
Would you share your experiment with me?
Best regards,
Jody
2007/7/31, Enno Luebbers <enno.luebbers@xxxxxxxxxxxxxxxx>:
Hello,
I'm currently investigating methods to implement hardware
multitasking on a Virtex-II Pro FPGA. One critical problem is
obviously the saving and restoring of the "context", that is the
internal state of a hardware module prior to replacement. I was
thinking about using partial bitstream readback to retrieve the
module's register and RAM states. If that module is to resume
operation later, one could easily use the readback frame data to
partially reconfigure the FPGA with the previous state.
This approach seems pretty straightforward. However, I see an issue
with the Virtex-II-Pro configuration architecture that would prove
prohibitive: Usually, when reconfiguring a (complete) FPGA, the IOB
and CLB register's initialization data embedded in the configuration
bitstream is loaded _FPGA-wide_ by issuing the GRESTORE command to
the CMD register. This ensures that all registers that have been
defined with an initialization value in the VHDL code, e.g.
...
signal mySignal : std_logic := '1';
...
are initialized to that value. When writing an active partial
bitstream, however, it is my understanding that the GRESTORE command
can not be used to restore state information, since it would reset
_all_ FPGA registers to the initial values, not just those in the
reconfigurable region.
Is there another way to use a partial readback bitrstream (with
embedded state information) to reprogram the same partially
reconfigurable region at a later time, in order to restore the
previous state information?
Best regards,
Enno
--
Dipl.-Ing. Enno Lübbers
Fachgebiet Technische Informatik
Universität Paderborn
Warburger Str. 100
33098 Paderborn
http://wwwcs.upb.de/cs/ag-platzner
Telefon: 05251 / 60-5397
Telefax: 05251 / 60-5377
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