Presented by:


from Google

Ron is an engineer at Google. He has been working with firmware and kernels, starting with the z80 and Unix v6, for many years. In 1999 he invented LinuxBIOS, now known as coreboot, running in every chromebook you see. In 2011, he created u-root (, which is the basis of much of his work of the last decade. In 2017 he started the LinuxBoot project (, which builds u-root and a Linux kernel into flash, replacing much of UEFI; this firmware model is now deployed at scale in Google data centers, as well as many others. His more recent work is the cpu command for Linux. He is President of the Plan 9 Foundation, and a member of the board of the lowrisc Foundation.

No video of the event yet, sorry!

Sourcery is a program that builds root file systems consisting mostly of Go source code: of the 90,000 files in a typical sourcery root, there are only 12 or so programs. Other programs are compiled on demand to a ramfs-backed file system. Compilation takes a fraction of a second for most programs, and never more than 2 seconds. Once the program is compiled to a statically-linked, tmpfs-based binary, invocation is instantaneous.

Because these images are mostly source, they can also be multi-architecture. Binaries present on boot have a path formed from the target os and architecture, e.g. /$OS_$ARCH/bin/init for init. Dynamically compiled binaries are placed in the tmpfs-backed /bin, since these binaries vanish on boot, the path can be simpler.

The file system includes the full Go toolchain as well as all source code. Constructing the root file system, including the git clone steps and Go toolchain build, takes under 4 minutes; each additional architecture takes another 90 seconds (to ensure reproducible builds, the Go toolchain builds itself 3 times).

Sourcery root file systems are designed for VFAT, a standard for firmware for x86, ARM, and RISC-V. A typical USB stick for sourcery would include a syslinux bootstrap for x86, required for those platforms; a kernel Image file for ARM; and a kernel file for RISC-V: the firmware for ARM and RISC-V is able to find boot kernels without using an on-stick bootstrap.

Sourcery may be found at

2022 June 4 - 10:00
25 min
Seminarraum 1
Open Source

Happening at the same time:

  1. State of transactional-update
  2. Start Time:
    2022 June 4 10:00