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kharobangdo
Adventurer
Adventurer
279 Views
Registered: ‎12-25-2014

Different bitsream is generated when I create & implement a project using the same tcl script multiple times

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Hi,

I am using Vivado 2019.2 & using VCU129 board.

I have a project compiled on VCU129. I generated tcl script using "write_bd_tcl". Using this tcl, I created & implemented the project 3 times. But 2 times, the bitstream matched with the original project & 1 time, the bitstream didn't match with original project.

Is this expected? Or should I get the same bitsream every time I run the tcl to generate the project?

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richardhead
Scholar
Scholar
267 Views
Registered: ‎08-01-2012

generating an identical bitstream is only garanteed when you have all of the following items identical:

1. Source code

2. OS

3. Vivado version

In addition, because of the way multi-threading works, you need to set the max threads parameter to 1, as multiple threads can cause differences in bitstream.

However, for us, we have noticed that often with Ultra scale, and more often with US+, the identical bitstream is generated with only the first 3 identical (and actually, we usually change a register "build ID", and still get the same bitstream). We however do not use any block designs. We have set max threads to 6.

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richardhead
Scholar
Scholar
268 Views
Registered: ‎08-01-2012

generating an identical bitstream is only garanteed when you have all of the following items identical:

1. Source code

2. OS

3. Vivado version

In addition, because of the way multi-threading works, you need to set the max threads parameter to 1, as multiple threads can cause differences in bitstream.

However, for us, we have noticed that often with Ultra scale, and more often with US+, the identical bitstream is generated with only the first 3 identical (and actually, we usually change a register "build ID", and still get the same bitstream). We however do not use any block designs. We have set max threads to 6.

View solution in original post