12-29-2014 05:44 PM
I have 64x2048 array of 32 bit numbers. I declare an array of this size and initialize it with an array initializer. I expect this to map to block ram (I have the ram_style = block attribute on the array). This simulates with VCS and works properly. I also have another design where a very similar array is mapped to block ram through synthesis. It seems that this is only a size issue and potentially it's an arbitrary number. Is there a way to increase the size synthesis expects to be able to handle?
The actual error is:
ERROR: [Synth 8-4556] size of variable 'mat_lin' is too large to handle; the size of the variable is 4194304, the limit is 1000000
01-14-2015 07:43 AM
01-05-2015 03:25 AM
01-05-2015 03:45 AM
01-05-2015 08:18 AM - edited 01-05-2015 08:30 AM
I am using 2014.4 and there is nothing interesting in the array. Just a straight static array which needs to be mapped to some block rams:
reg[63:0] RAM [2047:0][31:0];
One can split it into smaller pieces but it's a hassle and the limit is reached by using a small percentage of block rams in some devices. Also this array is initialized and the initializer will need to be regenerated by an updated script if the array is split. The limit is simply too low I think.
01-07-2015 11:21 PM
01-08-2015 02:09 AM - edited 01-08-2015 02:10 AM
It seems both synplify & xst can manage this size array without any problems so a CR was definitely needed. Thanks to Puli. I wonder what the new limit is going to be.
01-08-2015 02:22 AM
The limit was set based on some limitation earlier. We may have to wait for the update on the CR to get the new limit or a solution.
I see two options,
1. Fix the limit and provide a TCL command to change the limit as this is a soft limit.
2. Increase the memory limit.
01-14-2015 07:43 AM
05-26-2015 12:56 PM
Can you explain where this TCL parameter is set at? Was your 'set_param synth.elaboration.rodinMoreOptions "rt::set_parameter var_size_limit 4194304" ' command entered in a particular file?
This appears to be the solution to increasing the soft limit, I was hoping you could provide some guidance on how to implement it.
05-26-2015 02:01 PM