added binmft-misc

binfmt-misc.md

@@ -0,0 +1,80 @@
+# Binfmt support
+
+Binfmt allows you to run binaries from other architectures.
+
+This tutorial describes how to install `binfmt-support` and force kernel to preload, allowing it to freely run binaries from any architecture without the access to host `/usr/bin`.
+
+There are two possible method, depending on how new is your system:
+
+1. For new systems: Ubuntu Artful 17.10, Debian Buster,
+2. For older systems: everything else.
+
+## For new systems
+
+### 1. First make sure that you install needed `qemu-user-static`
+
+```bash
+sudo apt-get install -y qemu-user-static
+```
+
+### 2. Make sure that your kernel is recent enough, at least 4.8 which allows to preload architecture dependent files
+
+### 3. Add support for binfmts
+
+```bash
+sed -i '10s/^$/yes/g' /var/lib/binfmts/qemu-arm /var/lib/binfmts/qemu-aarch64
+```
+
+You may need to apply the same trick later if you update `qemu-user-static`.
+
+### 4. Reload configuration
+
+```bash
+systemctl restart binfmt-support
+```
+
+### 5. Test
+
+```bash
+docker run --rm -it arm64v8/busybox echo Hello World
+```
+
+## For old systems
+
+### 1. First make sure that you install needed `qemu-user-static`
+
+```bash
+sudo apt-get install -y qemu-user-static
+```
+
+### 2. Make sure that your kernel is recent enough, at least 4.8 which allows to preload architecture dependent files
+
+### 3. Add support for binfmts to `/etc/rc.local`
+
+```bash
+echo -1 > /proc/sys/fs/binfmt_misc/qemu-aarch64 || true
+echo -1 > /proc/sys/fs/binfmt_misc/qemu-arm || true
+echo ':qemu-aarch64:M::\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-aarch64-static:OCF' > /proc/sys/fs/binfmt_misc/register
+echo ':qemu-arm:M::\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-arm-static:OCF' > /proc/sys/fs/binfmt_misc/register
+```
+
+Run `/etc/rc.local` or restart system.
+
+### 4. Test
+
+```bash
+docker run --rm -it arm64v8/busybox echo Hello World
+```
+
+## Why and not `binfmt-support`?
+
+`binfmt-support` does not support `F` flag to preload architecture files,
+which is useful when you run container images for different architectures.
+
+Thus, this would not be possible:
+
+```bash
+docker run --rm -it arm64v8/busybox echo Hello World
+```
+
+The first `binfmt-support` version with the ability define `F` flag is 2.17. The 2.18 is distributed starting from Ubuntu Artful and Debian Stretch.