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Showing results for tags 'uvm_reg_field'.
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Hi all, I found a possible bug in the UVM register layer. It is in file uvm_reg_field.svh at line 728-730: // Assume that the entire field is enabled if (!be[0]) return; This causing a problem in a specific corner case. The following conditions need to met: - You have a bus in your env with byte enable feature, for example APB - You have a register in your design which have a register field which crossing a byte enable border, for example in a 16 bit register there is a 16 bit width field - In your env you monitor all your register accesses and the env calls the predict() function of the UVM register layer - You do a write access with byte enable 2'b10 or 2'b01 In the above described scenario the following will happen: - In case of byte enable 2b'01: In the DUT only the LSB byte will be written but in the register layer the whole field will be updated - In case of 2b'10: In the DUT the MSB byte will be written but in the register layer the register field will not be updated at all In both cases the contents of the register in the RTL and in the UVM register layer will be different. I think UVM should not assume that the entire register field is enabled or not. It should check if the entire field enabled or just part of it. I think it is a bug in the UVM package. Can you please confirm this is a bug? If so, is this bug known for the developers? If not, how can I open a bug report for it in Mantis? Regards, David
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In my test sequence, some fields of a register are changed frequently and others are keep previous value. I wrote the code like below, register.fieldY.set(value) register.update(status) // first update ... other code regsiter.fieldY.set(new_value) register.update(status) // second update The first update was processed but the second update was not seen in the system bus. I digged into UVM manual and implementation, and found out that 'update' function doesn't update mirrored value. By change, new_value was same to reset value of fieldY. So at that time the second update was called, m_mirrored and m_desired were same. That was the reason of no bus transaction. I tried below codes, and they updated my register properly. register.fieldY.set(value) register.write(register.get(), status) register.fieldY.set(value) register.update(status) register.predict(register.get(), status) However, they look like strange for me. Why I need to set desired value explicit by getting their internal desired value? Are my solutions wrong? Are there better ways in this case? -
Hi, I wanted to use the field.mirror() task provided in the uvm_reg_field class to check only a particular field. However, I see that the field.mirror() task is just calling the parent register mirror task. Hence the entire register is read and compared which I didn't intend to do. I tried this in my sequence and I see the above mentioned behavior. This looks like a serious bug. Can you please confirm this. Regards, Shreyas
