Significantly, the new endorsements seem to be driven by customer demand from large accounts. Avant! is the biggest EDA vendor to take a direct interest in Linux. The larger Mentor Graphics Corp. (Wilsonville, Ore.) owns most of Exemplar Logic, which recently pulled the plug on Linux support for its FPGA synthesis tool. The Alameda, Calif., company cited a lack of paying customers, as did Wellspring Solutions Inc. (Salem, N.H.) when it dropped Linux support for its Verilog simulator.

But an existing provider of Verilog simulation on multiple platforms, Fintronic USA (Menlo Park, Calif.), is reporting a sudden upsurge of interest in Linux. Alec Stanculescu, Fintronic president, said that Linux orders for the FinSim simulator went from 10 percent of the total a year ago to 20 percent within the last 12 months — and that 60 percent of current customer evaluations are using Linux.

The two largest EDA vendors, Synopsys and Cadence, are still hesitant to pick up the Linux banner. One reason is the high costs associated with supporting any new binary, said Phil Laidlaw, platform marketing manager at Cadence Design Systems Inc. (San Jose, Calif.). "It will take a large groundswell of customers to make the industry take notice — customers voting with their wallets," he said, "villagers with torches marching on the castle."

"We have not had serious [Linux] requests from paying customers," said Joe Laird, platforms marketing manager at Synopsys Inc. (Mountain View, Calif.).

According to Gary Smith, principal EDA analyst at Dataquest Inc. (San Jose), the trouble with Linux is support. He said one EDA vendor sold four Linux products, all using different versions of Linux, which required four support people for four orders.

The vendors who are now adopting Linux said times are changing. EDA on Linux has become considerably easier, they said, due to commercial support from Red Hat Software Inc.; availability of ancillary products, such as debuggers, under Linux; and the desire of some customers to plug PC hardware into existing Unix networks.

Good fit with Unix
Fintronics' Stanculescu attributed the upsurge in interest to two factors: availability of the Undertow debugging environment from Veritools Inc. (Palo Alto, Calif.) on Linux, and the desire of users to set up large "compute farms" consisting of high-performance, low-cost PCs. "Linux fits better into Unix environments than NT would fit," he said.

"We have some large potential customers who want to buy Polaris on Linux," said Chi-Ping Hsu, a member of the chief executive officer staff for products at Avant! "We have been resistant to port to Linux, but with the recent public interest and with Red Hat support, we felt we would try this product first." Hsu said that two large accounts, which already use Linux internally, are interested in the Polaris port. "There does seem to be a trend that regression simulations can be offloaded to cheaper hardware, and that the preferred OS may be Linux," Hsu said.

Avant! doesn't plan to announce a Linux version of Polaris until November, Hsu said. Pricing will be the same as for Unix versions. Previously offered by Frontline Design Automation before its acquisition by Avant!, Polaris combines event-driven and cycle-based Verilog simulation.

Meanwhile, the SignalScan debugger has been shipping on Linux since September, said Steve Pollock, vice president of marketing at Design Acceleration (San Jose). "We're starting to see a groundswell of support for Linux in certain pockets," he said. "We're selling it, and people are asking for it."

Another Verilog debugging supplier, Novas Software (Campbell, Calif.), may soon join the ranks. "We have had Linux inquiries from design engineers. Linux is viewed as solid, reliable and supportable. We are seeing enough interest that we are rethinking our plans for Linux," said Dale Pollek, Novas vice president of marketing and sales.

The SpeedSim Verilog cycle-based simulator from Quickturn Design Systems Inc. (San Jose) also offers Linux support, and several customers run it on Linux compute farms consisting of PCs.

Changing kernel
Though Wellspring's decision to drop its Linux support leapt to the forefront in the Linux EDA e-mail reflector in the last week, that actually happened two years ago, said Elliot Mednick, Wellspring's president. "It needed more support than Windows because at the time, the kernel was changing pretty often," he said. "For every distribution of Linux there was something different." (The Linux EDA e-mail reflector, which tracks user and vendor activity with Linux-based EDA, can be accessed if requested by e-mail.)

In those early Linux days, Mednick said, Wellspring found that people interested in that OS were mostly looking for free software. "We have been getting more requests lately, and with Red Hat doing more support, more serious users are starting to pick it up," he said.

In the Linux EDA e-mail reflector, two designers wrote to say they'd tried the Wellspring VeriWell simulator under Linux, but found it unreliable or had problems with library support. Mednick acknowledged that third-party library support was a problem.