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Thoughts dereferenced from the scratchpad noise.

Latest posts


debos in docker - the second attempt

Published at August 23, 2018 · Maciej Pijanowski ·  5 min read

Intro In the previous post, I have shared my first experience with the Debian images builder - debos. I have posted my current results on the issue but since there was no response, I’ve decided to try to move forward by myself. Just to remind - I was stuck at the following error (when building for arm64): 1 2 3 4 5 6 7 8 9 10 11 12 2018/07/26 18:36:39 Debootstrap (stage 2) | chroot: failed to run command '/debootstrap/debootstrap': Exec format error 2018/07/26 18:36:39 debootstrap....

Categories: os-dev

Xen HVM guests on PC Engines apu2

Published at August 16, 2018 · Piotr Król ·  15 min read

Continuing blog post series around Xen and IOMMU enabling in coreboot we are reaching a point in which some features seem to work correctly on top of recent patch series in firmware. What we can do at this point is PCI passthrough to guest VMs. Previously trying that on Xen caused problems: random hangs firmware cause Linux kernel booting issues (hang during boot) IOMMU disabled - unable to use PCI passthrough Now we can see something like that in dom0:...

Categories: firmware os-dev

Our first look at debos - new Debian images generator

Published at July 27, 2018 · Maciej Pijanowski ·  7 min read

What is debos debos is quite a new tool allowing easier Debian images generation. It seems to be following current trends - it is written in Go, using YAML as an input format. The idea of taking away debootstrap shell scripts and replacing it with a single, simple YAML file looks tempting enough to give it a try. Full feature description can be found in this introductory post on Collabora’s blog....

Categories: os-dev

How to boot Xen over PXE and NFS on PC Engines apu2

Published at July 18, 2018 · Piotr Król ·  9 min read

From time to time we face requests to correctly enable support for various Xen features on PC Engines apu2 platform. Doing that requires firmware modification, which 3mdeb is responsible for. Xen have very interesting requirements from firmware development perspective. Modern x86 have a bunch of features that support virtualization in hardware. Those features were described in Xen FAQ. It happens that most requesting were IOMMU and SR-IOV. First, give the ability to dedicate PCI device to given VM and second enables so-called Virtual Functions, what means on a physical device (e....

Categories: firmware os-dev

Basics of x86 assembly (AT&T syntax)

Published at May 17, 2018 · Bartek Pastudzki ·  12 min read

Nowadays, application of programming in assembly language is very small. Writing production code in assembly may be found in the most demanding tasks in embedded. Even in modern firmware (coreboot, EDK2) most of the code is written in C. Honesly, that’s quite undestandable, assembly code isn’t easy to read nor write and some state that it’s no longer needed to be known. In my opinion, that’s far from the truth....

Categories: programming

The art of disassembly

Published at April 27, 2018 · Bartek Pastudzki ·  12 min read

Probably there was never a programming language that would fascinate me as much as assembly. In fact, it was my second “real language” (after Pascal/Delphi and DOS batch) and the first one I would really understand. Of course, the internals of protected mode initialization was too much for 15-year-old and I finally moved to C and *nix shell. Anyway, I always liked the feeling that I know what I’m really doing but more complex languages are needed nowadays....

Categories: programming

Building EDK2 based firmware for MinnowBoard

Published at April 3, 2018 · Bartek Lew ·  2 min read

Building EDK2 based firmware for MinnowBoard There are some options to build firmware for MinnowBoard, a Bay Trail based SBC (Single Board Computer) from Intel. We prefer usually coreboot as simplest and fastest, open source solution, but sometimes we want to have UEFI interface. UEFI itself doesn’t cover whole boot procedure, so its open source reference implementation, EDK2 is not enough to build firmware for hardware plafrorm, we need to provide PI (Platform Initialization) phase implementation....

Categories: firmware

Building UEFI based firmware on MinnowBoard

Published at March 28, 2018 · Bartek Pastudzki ·  8 min read

Building coreboot on well supported platform such as Bay Trail is quite straightforward task, however we need to remember about some things in order to have coreboot working. First of all we need to provide up-to-date microcode and FSP (Firmware Support Package), which are not included in coreboot source tree and coreboot build system won’t complain about it. Second thing is that Bay Trail has TXE firmware on the same ROM as boot firmware so we have to make sure that we won’t corrupt it because it would brick the platform....

Categories: firmware

Minnowboard Turbot remote firmware flashing with RTE (Remote Testing Environment)

Published at March 23, 2018 · Arkadiusz Cichocki ·  7 min read

Minnowboard Turbot remote firmware flashing with RTE (Remote Testing Environment) Introduction Work related to a hardware carries some restrictions which don’t occur when working only with a software. One of them is a limited number of devices. This one may cause a problem with a accessibility to the platform. The limited number of users could slow development and testing. What is more work with a hardware requires a minimal knowledge of the theory of circuits and signals to eliminate platform damage by a user....

Categories:

Flashing eMMC on Hummingboard Edge using fastboot? part 1

Published at March 20, 2018 · Maciej Pijanowski ·  9 min read

Introduction Flashing an eMMC of produced board is one of the crucial manufacturing procedures. This post series presents how one can take advantage of i.MX6 features and open source tools to prepare themselves with quite robust and easy to use process. Target reference platform is Hummingboard Edge. General concept The general concept is inspired by this great bootlin (former FreeElectrons) post: I’ve run into some issues while trying to do something similar on Hummingbard Edge, so decided to share my experience....

Categories: app-dev firmware