( ESNUG 301 Item 2 ) --------------------------------------------- [10/15/98]
From: "Tom Harrington" <tharring@ford.com>
Subject: The New Design Budgeting Features In DC 98.08 Have Serious Problems
John,
If you've got DC 1998.08, and are interested in the new design budgeting
features, let me save you some time and frustration:
* It looks good if you run it from the new budget_shell tool (though I
have not done a detailed analysis of results yet).
* It just plain does not work from dc_shell. Don't bother.
I downloaded the EST update that's supposed to add design budgeting to
dc_shell. I suppose I should have taken it as a bad omen when the EST
file was called "db-1998.08.zip" and I was using a Unix system. Synopsys
support insisted that Solaris 2.5.1 has an "unzip" command. I didn't
find one, and no tool I could find would open it. I went back and forth
with support on this for a week before they decided to send me an unzip
tool.
For the record, the package contains:
* A file called $SYNOPSYS/admin/setup/budget.setup.e, which apparently
contains the code for the budgeting commands.
* Man pages in both Unix "man" format and HTML.
* A couple of support scripts: a new system-wide .synopsys_dc.setup and
one called $SYNOPSYS/auxx/syn/budgeting/scripts/write_gdb.dcscr
I dutifully read the man pages for the allocate_budgets and
allocate_hierarchical_budgets commands. Both said that the commands
"invoke the budget_shell allocate_hierarchical_budgets command". I
wasn't sure what the difference was, so I picked one to experiment with.
I wrote a script that basically tried to reproduce the sample code
contained in the docs. I tried to budget a design with:
dc_shell> allocate_budgets -verbose -db design_name.db -file_format_spec
"characterization/%D_budget.scr"
I got:
Error: unknown option '-file_format_spec' (CMD-010)
Synopsys support told me, despite the man page, "-file_format_spec" is only
available for command "allocate_hierarchical_budgets."'. OK, fine. I
deleted the option:
dc_shell> allocate_budgets -verbose -db design_name.db
<...much output snipped...>
Error: Must specify one of these options: cell_list or -incremental.
(CMD-004)
Huh? Neither of those are on the man page... I wondered if I should be
using allocate_hierarchical_budgets instead:
dc_shell> allocate_hierarchical_budgets -verbose -db iopsm_8.db
Error: Undefined operator on or near line 20 at or near
'allocate_hierarchical_budgets'. (EQN-2)
In other words, "what's 'allocate_hierarchical_budgets', kemo sabe?"
In response, I learned the following from Synopsys support:
* If you have done any manual design budgeting (such as the new
"set_user_budget" command) before using allocate_budgets, you
must budget with the "-incremental" option. Score another for
good documentation, since this was never mentioned. Of course,
since I didn't do any manual design budgeting, this answer
really fails to address the issue.
* Documentation and previous statements from support notwithstanding,
allocate_hierarchical_budgets is only available in PrimeTime. That is,
there's a man page for it under dc_shell, but the command isn't actually
available!
My overall impression is that Synopsys just completely skipped any testing
on the dc_shell -> design budgeting interface. The EST could not be opened
with standard Unix tools. And once installed, the tools either failed to
work or failed to exist. To top it off, they were accompanied by
documentation that, between missing crucial options and adding nonexistent
ones, seem to be little more than bad science fiction.
As I said earlier, though, the commands do seem to work as advertised in
the new budget_shell tool. Hopefully we won't have to wait for 1999.0X
for the dc_shell interface to be fixed.
- Tom Harrington
Ford Microelectronics Colorado Springs, CO
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