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benou | 10 months ago

Here is an example of preparing a debian ARM image on x86 with debootstrap, qemu and chroot:

  ~# sudo apt install qemu-user-static debootstrap
  ~# mkdir /tmp/arm
  ~# debootstrap --foreign --arch=armhf buster /tmp/arm http://deb.debian.org/debian
  ~# cp /usr/bin/qemu-arm-static /tmp/arm/usr/bin/
  ~# chroot /tmp/arm   # from that point, you're running ARM!
  ~# /debootstrap/debootstrap --second-stage

discuss

seba_dos1|10 months ago

These days (with recent kernels) you don't even have to copy the qemu binary into the rootfs nor use a static binary - these used to be workarounds for things that kernel now handles on its own.

fsniper|10 months ago

This is very cool! I had no idea you could chroot into different architectures.

ranger_danger|10 months ago

Well technically you can't, in the sense that chroot has no idea you're doing it... the magic of binfmt support in the kernel (setup for qemu by the post-install script for qemu-user-static I believe) basically lets you run any architecture's binary that qemu-user-* supports just by trying to execute it natively, it basically just translates the execution of "./other-arch-cmd" into "qemu-user-static ./other-arch-cmd".