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August 31, 2016

Daniel V asked about best practices for designing and manufacturing open source hardware. Rich Felker and Jeff Dionne replied talking about tool flow, I/O devices, and design choices we made in the Turtle prototypes.

August 30, 2016

Rich Felker asked about reviving support for the Avnet LX9 Microboard, an older FPGA board which some early j-core development was done on. There was some interesting discussion of tools, but the board no longer appears to be widely available.

August 23, 2016

Cedric Bail asked about framebuffer support, X11, and wayland. Jeff noted the HDMI output in the upcoming turtle boards (and later posted a trivial HDMI test program to show how the signal generation works), and the discussion continued into using DMA for hardware acceleration and framebuffer implementation.

August 21, 2016

A question about fdpic vs binflt got a response from Rob pointing at Rich's FDPIC toolchain and from Rich describing the internals. (The original posting of the SH uClinux FDPIC ABI is here.)

August 20, 2016

Jeff answered more questions about j-core ASIC development.

August 17, 2016

Rob asked about Google Fuchsia (and whether it's relevant to j-core), and poked its developers.

August 16, 2016

A thread about learning VHDL and the two process design method j-core uses led Geoff to talk about j-core package layout a bit, and post some simulator-based hello world code.

Others had their own suggestions for VHDL tutorials.

August 15, 2016

Alas, only half the j-core support made it upstream into vanilla this time. The timer and interrupt controller support is still stuck in some reviewer's tree. So it's in, it builds, but hangs during boot.

August 12, 2016

The ongoing distribution thread is discussing what it would take to configure a little endian j-core.

Meanwhile a second thread started, speculating about a nommu debian port.

August 8, 2016

J-core support has been merged into the vanilla kernel, and should be in 4.8.

August 7, 2016

Brian Bartholomew asked about Linux distributions for j-core kicking off a long thread.

August 5, 2016

Numato sells an ethernet expansion that should work with j-core, if anyone wanted to tweak the VHDL to wire it up.

We've submitted a j-core talk proposal for linuxconf.au.

August 2, 2016

A thread on what it would take to run Linux on J1 started here and covered things like cache prefetch, cmpxchg implementation, memory model for atomic writes...

Another post explained why the third release should be 62.5 mhz instead of 66.

July 29, 2016

Rich helped Brian Bartholomew debug a Numato serial port issue so Brian could demo j-core at his local hackerspace.

July 23, 2016

Update on NVC progress.

July 21, 2016

Robert and Rich had an exchange about illegal instruction trap behavior in Linux, and Geoff wrote about running Leingen.

Robert put his patches up on github

July 20, 2016

Robert Ou submitted a pair of patches implementing illegal instruction traps.

July 19, 2016

Robert Ou got j-core running under myhdl simulation, and found a hardware bug (which is really that j2 is behaving like sh4, not sh2, and which we hadn't previously noticed because gcc doesn't produce that code even when targeting sh2).

Geoff Salmon explained how J-core uses VHDL configurations, and how to reset the CPU, with a follow-up from Jeff about how the boot ROM in the FPGA isn't. Jeff also talked about our VHDL to silicon toolset for an eventual J-core ASIC.

Jeff explained what the v2p tool does (adding a "register" keyword to VHDL).

July 12, 2016

A thread on the mailing list explained that neither unaligned access or illegal instructions currently generate a trap, because we haven't bothered to implement that yet. (It's not hard, we just need to do it in a way that doesn't impact clock frequency.)

June 27, 2016

Quick status report on merging vanilla kernel support and status of the Turtle Board.

June 21, 2016

The J-core engineers got together in Austin, and Rob did a brief writeup.

A thread about using J-core on Kintex 7 led to an explanation of the memory_fpga.vhd module, and later an explanation of the two instr_bus types.

June 12, 2016

The bug causing timing differences between NVM and GHDL's simulation of J1 running its self-test got fixed, and the NVC maintainer let us post the email thread about it.

Next up is trying to simulate J2 with NVC.

Jeff also posted a diff of J1 against the J2 tree so you can see how this work eventually merges upstream as a configuration option.

June 10, 2016

Geoff explained how the DDR controller is configured on Numato boards, and updated his previous instructinos about porting J-core to more FPGA boards.

June 5, 2016

If you'd like to reproduce the new nvc simulator and run the tiny J1 prototype VHDL build, updated instructions are available.

In future, we want to combine this with yosys to produce a fully open source VHDL to FPGA bitstream toolchain, and we're actively working through the issues on the way there.

The NVC maintainer says he has a block of time coming up to work on it, so now is an excellent time to try it out and make suggestions or report bugs.

June 3, 2016

The simple root filesystme build script is on github now.

May 25, 2016

The kernel build instructions didn't mention how to get a device tree and install it on your board. (Oops.)

May 21, 2016

Added J1 to the roadmap, following several days of list discussion.

May 20, 2016

Christopher Friedt has been updating QEMU towards providing a Numato board emulation capable of running J2's ROM bootloader and vmlinux images.

Since the J2 bootloader starts with CPU instruction verification tests the existing qemu-system-sh4 emulation doesn't pass, he's spending a lot of work Fixing QEMU's superh instruction emulation.

May 18, 2016

A simple root filesystem build script was posted to the mailing list, along with updated instructions on building the cross compiler and kernel.

May 11, 2016

The first ten Turtle Board prototypes have arrived in Japan. They are adorable.

They boot Linux with working serial and ethernet. We've also confirmed HDMI output works, but haven't yet done the VHDL for a proper framebuffer the existing kernel drivers can understand.

The USB hub has a wire connected wrong, but that's why we have prototypes. We also need to move three components a milimeter or so to make them fit in the official Raspberry Pi case without filing the edges.

May 5, 2016

Added a talks page linking to the video of our ELC 2016 J-core design walkthrough talk, and linking to several historical talks.

May 1, 2016

Added a Roadmap page describing j3 and j4 development plans.

April 30, 2016

More from the mailing list:

April 28, 2016

Several interesting mailing list threads:

April 27, 2016

J-core received a nice writeup from EE Journal.

(Although to slightly correct it: musl's got threads working fine. That's part of the reason we added a cmpxchg instruction. Traditional sh2 couldn't do modern futex-based thread synchronization properly, but we're fixing things like that as we go.)

April 26, 2016

We're attempting to organize an Open Hardware track at this year's Linux Plumber's Conference. It's not j-core specific, but many of the j-core developers plan to attend if the track is approved.

If you'd like to attend, or have suggestions for topics we should cover or potential presenters to contact, please edit the proposal's wiki page.

April 18, 2016

The second source release is now up. Links on the main page have been updated, and direct downloads are available in the downloads directory. See the release announcement on the mailing list for details.

April 17, 2016

On the mailing list, Christopher Friedt and Trevore Woerner figured out what Ubuntu did wrong that made the Numato bitstream flashing tool unreliable on Ubuntu 14.04, and we've documented how to remove Ubuntu's "any serial device plugged into a modern computer is a modem, so send random AT commands at it" daemon.

April 15, 2016

The mailing list is live.

April 10, 2016

Added a navigation bar to the web page, which should make it a bit easier to find this news page. :)

For those of you asking, the Turtle board kickstarter isn't up yet, we're aiming for sometime next month. We'll be adding a turtle page to the nav bar when we have more to say about that.

April 9, 2016

Slides from our ELC talk are online. Video was recorded but the Linux Foundation usually takes a few weeks to post it on their youtube channel.

April 6, 2016

Our J-Core design walkthrough talk at ELC went well, Jeff Dionne and Rob Landley spoke to a packed room for an hour, and the video should go up on youtube whenever ELC gets around to processing it.

Here are the slides.

April 2, 2016

Welcome to the new j-core.org. This site supercedes the old websites (nommu.org/jcore, 0penc0re.org, and 0pf.org) providing a new home for j-core processor development.

Please update your bookmarks accordingly.

Thanks to Core Semiconductor for hosting this wesite and contributing engineering time and hardware to the J-core project.