Go2UVM - UVM tit-bits
Go2UVM.org the premier UVM support site clarifies
common UVM queries from users
Read along to learn this tech-tip, contact us if you want to
experiment these and many more hands-on UVM via:
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2014-2016, www.go2uvm.org
UVM - m_sequencer vs. p_sequencer
During One of our international UVM training classes held at
Vietnam, a customer asked about:
We still confused about the usage of p_sequencer and m_sequencer
2014-2016, www.go2uvm.org
UVM Sequence & SQR
UVM has 2 key OOP inheritance trees
Transaction
Component
UVM also provides bridge betn the these 2 trees
m_sequencer
2014-2016, www.go2uvm.org
UVM m_sequencer
This pointer m_sequencer is to be set before the
sequence body can be executed
Usually it is done via series of method calls
internally.
User code: uvm_test::main_phase() seq.start
(sqr_0)
Internally it calls seq.start(sqr_0) (Coded in
uvm_sequence_base class)
start(sqr_0) -> set_item_context(sqr_0) ->
set_sequencer(sqr_0)
// m_sequencer = sqr_0;
2014-2016, www.go2uvm.org
UVM m_sequencer
Typical applications of m_sequencer:
Change arbitration mode of a sequencer (via
m_sequencer.set_arbitration())
Accessing component hierarchy from within SEQ
body
While built-in m_sequencer variable is handy,
it is of type uvm_sequencer_base
Hence no access to derived SQR
members/variables
Cant be used to access VSQR members/variables
2014-2016, www.go2uvm.org
UVM Virtual Sequencer
Typical IP verification requires more than one
sequencer/interface
UVM uses a term virtual sequencer to denote a wrapper
around multiple sequencers
SPI Interface
spi_ctrl_env
2014-2016, www.go2uvm.org
UVM Virtual Sequencer
class vl_apb_spi_vsqr extends uvm_virtual_sequencer;
Subsequencers
apb_sqr apb_sqr_0;
spi_sqr spi_sqr_0;
function new (string name = " vl_apb_spi_vsqr",
uvm_component parent);
super.new(name,parent);
endfunction:new
`uvm_component_utils(vl_apb_spi_vsqr)
endclass : vl_apb_spi_vsqr
2014-2016, www.go2uvm.org
Why not m_sequencer for Virtual SEQ?
A virtual sequence co-ordinates multiple sequences on
multiple sequencers
class vl_apb_spi_vseq extends uvm_sequence;
`uvm_object_utils(vl_apb_spi_vseq)
ERROR
task body();
apb_seq.start(m_sequencer.apb_sqr_0); // Run APB on apb_sqr_0
spi_seq.start(m_sequencer.spi_sqr_0); // Run SPI on spi_sqr_0
2014-2016, www.go2uvm.org
UVM Virtual SEQ & p_sequencer
A virtual sequence co-ordinates multiple sequences on
multiple sequencers
UVM provides a p_sequencer option
class vl_apb_spi_vseq extends uvm_sequence;
`uvm_object_utils(vl_apb_spi_vseq)
// Set the p_sequencer and other book keeping
stuff
`uvm_declare_p_sequencer(vl_apb_spi_vsqr)
2014-2016, www.go2uvm.org
Use p_sequencer for Virtual SEQ
A virtual sequence co-ordinates multiple sequences on
multiple sequencers
class vl_apb_spi_vseq extends uvm_sequence;
`uvm_object_utils(vl_apb_spi_vseq)
// Set the p_sequencer and other book keeping stuff
`uvm_declare_p_sequencer(vl_apb_spi_vsqr)
task body();
apb_seq.start(p_sequencer.apb_sqr_0); // Run APB on apb_sqr_0
spi_seq.start(p_sequencer.spi_sqr_0); // Run SPI on spi_sqr_0
2014-2016, www.go2uvm.org
Summary
Go2UVM.org the premier UVM support site clarifies
common UVM queries from users
Contact us if you want to experiment these and many more
hands-on UVM via:
training@cvcblr.com
+91-9620209223
http://www.fb.com/cvc.uvm
https://www.linkedin.com/company/cvc-pvt-ltd
http://www.twitter.com/cvcblr
2014-2016, www.go2uvm.org
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