ESL – Page 3 – Observations from Uppsala

Adding to Schirrmeister’s Virtual Platform Myth Busting

Frank Schirrmeister of Synopsys recently published a blog post called “Busting Virtual Platform Myths – Part 1: “Virtual Platforms are for application software only”. In it, he is refuting a claim by Eve that virtual platforms are for application-level software-development only, basically claiming that they are mostly for driver and OS development and citing some Synopsys-Virtio Innovator examples of such uses. In his view, most appication-software is being developed using host-compiled techniques. I want to add to this refutal by adding that application-software is surely a very important — and large — use case for virtual platforms.

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Eclipse Linux Kernel Indexing Works

Edited on 2009-Feb-01, to include the link to the illustrated guide that really helps you get there faster. Thanks Simon! Also, promoted to front page, original post was put up on 2008-Nov-09.

Thanks to Simon Kågströms post (and the even better second-generation with screenshots) about using Eclipse for the Linux kernel, I have a much nicer work environment now for my ongoing work in learning Linux device drivers on PowerPC, which has helped me work my way through several hard-to-figure-out system calls. Continue reading “Eclipse Linux Kernel Indexing Works”

EDA Tech Forum Article on Ecosystem Enablement

I have an article about ecosystem enablement for new hardware, co-authored with Richard Schnur of Freescale published in the December 2008 issue of EDA Tech Forum. The core concept is that a virtual platform solution makes it possible to get a new chip to market faster with better software support, and even enables virtual design-in of a chip at OEM customers before hardware becomes available. The article builds on our joint experience with the QorIQ P4080 launch in the Summer of 2008, where we had several operating systems and middleware packages in place at the moment the chip was announced. EDA Tech Forum requires registration, but it was still free, and there are many other good articles available.

Threading or Not as a Hardware Modeling Paradigm

gears-modeling Traditional hardware design languages like Verilog were designed to model naturally concurrent behavior, and they naturally leaned on a concept of threads to express this. This idea of independent threads was brought over into the design of SystemC, where it was manifested as cooperative multitasking using a user-level threading package. While threads might at first glance look “natural” as a modeling paradigm for hardware simulations, it is really not a good choice for high-performance simulation.

In practice, threading as a paradigm for software models of hardware circuits connected to a programmable processor brings more problems than it provides benefits in terms of “natural” modeling.

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Notes from the IP 08 Panel

Now I am home again, and some days have passed since the IP 08 panel discussion about software and hardware virtual platforms. This was an EDA hardware-oriented conference, and thus the audience was quite interested in how to tie things to hardware design. Any case, it was a fun panel, and Pierre Bricaud did a good job of moderating and keeping things interesting.

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Gary Stringham on Hardware Interface Design vs Virtual Platforms

I just read an interesting paper from the 2004 Embedded System’s Conference (ESC) written by Gary Stringham. It is called “ASIC Design Practices from a Firmware Perspective” and straddles the boundary between hardware design and driver software development. It was good to see someone take the viewpoint of “how you actually program a hardware device is as important as what it does”. Gary seems to understand both the hardware design and implementation view of things, as well as that of the embedded software engineer. To me, that seems to be a fairly rare combination of skills, to the detriment of our entire economy of computer system development.

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Cadence-Ran vs Synopsys-Frank over Low-Power and Virtual Things

Over the past few weeks there was a interesting exchange of blog posts, opinions, and ideas between Frank Schirrmeister of Synopsys and Ran Avinun of Cadence. It is about virtual platforms vs hardware emulation, and how to do low-power design “properly”. Quite an interesting exchange, and I think that Frank is a bit more right in his thinking about virtual platforms and how to use them. Read on for some comments on the exchange.

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Shaking a Linux Device Driver on a Virtual Platform

To continue from last week’s post about my Linux device driver and hardware teaching setup in Simics, here is a lesson I learnt this week when doing some performance analysis based on various hardware speeds.

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Learning Linux Device Drivers on a Virtual PowerPC

There are times when working with virtual hardware and not real hardware feels very liberating and efficient (not to mention safe). Bringing up, modifying, and extending operating systems is one obvious such case. Recently, I have been preparing an open-source-based demonstration and education systems based on embedded PowerPC machines, and teaching myself how to do Linux device drivers in the process. This really brought out the best in virtual platform use.

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Cadence on Virtual Prototypes instead of Host Execution

Cadence technical blogger Jason Andrews wrote a short piece a couple of days ago on his perception that host-based execution is becoming unncessary thanks to fast virtual platforms. In “Is Host-Code Execution History“, he tells the story of a technique from long time ago where a target program was executed directly on the host, and memory accesses captured and passed to a Verilog simulator. The problem being solved was the lack of a simulator for the MIPS processor in use, and the solution was pretty fast and easy to use. Quite interesting, and well worth a read.

However, like all host-compiled execution (which I also like to call API-level simulation) it suffered from some problems, and virtual platforms today might offer the speed of host-compiled simulation without all the problems.

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ChipDesignMag Article on Software in Hardware Design

Chip Design Magazine published an article by me in their August/September 2008, about Getting Software into the Hardware Design Loop. The article is about the technical and marketing aspects of how chip designers can get early feedback from software and systems designers, early in the hardware design process. The vehicle for this? Virtual platforms, obviously.

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Architecture Exploration by Free Market

This is a short maybe heretic post on the topic of architecture exploration.

It just struck me the other day that the idea prevalent in chip design that you want to explore the design space of a certain with great detail and precision might be the wrong way to go about things. It is in some sense similar to the ideas of planned economies: you decide a priori what is important, and try to optimize the design to do just that. If you are right, it is brilliant. If you are wrong, it can be very wrong. That is scary to say the least. It seems to assume that you have a pretty good idea of what you need to achieve, and that this is not likely to change for the lifetime of a design.

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Software, Hardware, and Development Methods

opinion I just read an opinion-provoking piece “Software developer attitudes: just get on with it” by Frank Schirrmeister, as well as the article “Life imitating art: Hardware development imitating software development” by Glenn Perry that he linked to. Both these articles touch on the long-standing question of who does development the “best” in computing. I have heard these arguments many times, where software developers think that there is something mythical about hardware development that makes things work so much better with much fewer bugs, and hardware people looking at the speed of development and fanciful fireworks of coding that software engineers can do. It could be a case of the grass always looking greener on the other side… but there are some concrete things that are relevant here.

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Schirrmeister has a nice observation on model-based development

Model-based architecture (MDA) or model-based development is an idea that to me comes from the automotive field. To, it means that you use some tool that is capable of modeling both a computer controller system and the environment being controlled to create a simulation world where computer control and environment meet and the characteristics of the controller can be ascertained quickly. The key is to not have to convert controller algorithms to concrete code, and not have to run concrete code on concrete hardware against physical prototypes to test the controllers. Today, this seems to be applied to many fields where you are creating control systems (automotive, aviation, robotics). The tools are math-based like MatLab and LabView, along with special programming environments based on UML and StateCharts.

What is interesting is that most of these tools are graphical in nature. And they do seem to work quite well, which is quite surprising given the otherwise poor record of graphical programming as opposed to text-based programming. There were a pile of graphical programming environments in the 1980’s, none of which amounted to much. What survived and prospered were the good old text-based languages like C, C++, Java, VisualBasic, etc. In practice, it seems like it is very hard to beat sequential text when it is time to actual get code working. More efficient programming seems to boil down to having to write less text and having text which is easier to write (for example, dynamic typing, rich libraries, garbage collection, and other modern language features that remove intellectual burdens from the programmer).

But graphics do seem to work for domain-specific cases (like control engineering or signal processing), especially for data-flow-style problems. And for abstract architecture work. So there has to be something to it… but what?

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Book review: Taxonomies for the … Digital Systems

The book “Taxonomies for the Development and Verification of Digital Systems“, edited by Brian Bailey, Grant Martin, and Thomas Andersson, was published in 2005 by Springer Verlag. It is a legacy of the defunct VSIA, and presents an attempt to bring order to nomenclature and taxonomies in the chip design field (its scope is defined to be broader than that, but in essence, the book is about SoC design for the most part).

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