About The Project

FNOB was firstly introduced in DVCon.US 2022, and attracted lots of interests from industry.

TL;DR

“Fnob” as Command-line Dynamic Random Generator, is a novel methodology to improve the implementation of constrained-random, with below advantages compared to conventional constraint syntax:

• It produces less error prone testbench coding by taking advantage of predefined templates of each randomization type, which are flexible to take any number of variable sets.
• Faster random regression bring-up with the ability to override both random type and value through either in-line or command-line override, instead of additional constraint coding and re-compile.
• Faster DV coverage closure can be achieved by having embedded Fnob coverage on stimulus side, instead of additional functional coverage coding on checking side.

Use the fnob_readme.txt to get started.

Getting Started

Add fnob_pkg.sv file into your compilation flow.

Usage

General APIs

//fnob_db::set     - Create and register fnob variable in fnob_db
//generate a number in [300-100:300+100] that distributed in Gaussian distribution
fnob_db#(bit[63:0])::set("m_fnob_norm", FNOB_NORM, '{"val":'{300, 100}});

//fnob_db::gen - query the fnob varaible for a random number
fnob_db#(bit[63:0])::gen("m_fnob_norm"))

//fnob_db::val - query the fnob varaible for current value
fnob_db#(bit[63:0]::val("m_fnob_norm"))

Use the fnob_test.sv to get more use case examples.

Override

// To override within SV file:
uvm_config_db#(string)::set(null, "*", "<fnob_name>", "<type>:<val_str>");

// To CLI override in TB:
runopts/plusargs:  "+uvm_set_config_string=\*,m_fnob_profile_delay,profile:0:10:100:1000_5:1"

The primary purpose that we open source the project is to engage not just more users, more importantly, developers for the FNOB community. Any new random type that is highly reusable that currenlty not supported, we encourage everyone to become a developer and commit it!

Steps to add a new random type

// Step 1: fnob_rand.sv

1.1. create new class extends from fnob_rand#(T), add your random implementation; (follow examples of other classes)

1.2. must have three routines: new(), init(), gen();

// Step 2: fnob_common.sv

2.1. Add your new random type enum in FNOB_TYPE;

2.2. Add typedef of your new class;

2.3. Add your new enum translation in param_2_rand and s_2_type;

// Step 3: fnob_test.sv

3.1. Create your new fnob in standalone; add comment above instantiation to explain meaning of params;

3.2. Test your new fnob in standalone way:

3.2.1. Run command at the top of fnob_test.sv

3.3. Add your new fnob in test_override to test config_db override of new type;

Advanced Applications

fnob_reg_seq

fnob_reg_seq is a uvm_reg_seq that flattens all uvm_reg_field into fnob_type, enabling user to pass down register field with random value directly.

//example
fnob_seq = fb_pkg::fnob_reg_seq::type_id::create("m_fnob_seq", this);
fnob_seq.set_root_block(rm);    //set root RAL
fnob_seq.start(env.ahb_agent.sqr);   //start the reg seq on sequencer. 
...

//CLI interface: user could directly tweek randomization with "fnob_<reg_field_name>" 
+uvm_set_config_string=\*,fnob_hs_scaling_type_f,unif:0:3

Contact

Haoxiang Hu - haoxhu@fb.com Tuo Wang - tuow@fb.com

Copyright

Copyright (c) Meta Platforms, Inc. and affiliates.

All licenses in this repository are copyrighted by their respective authors. Everything else is released under CC0. See LICENSE for details.