Kernel Support for miscellaneous Binary Formats

In cross-development, sometimes you want to build a linux sysroot of different architecture on your filesystem. Then, you want to use Debain ways (dpkg) to build that root filesystem. Basiclly, you have a debian package, and you want to use "dpkg -i" to install that package in the root filesystem.

The problem here is that dpkg will call "chroot" to that sysroot and invoke some post install scripts. However, on that filesystem, /bin/bash is a binary of different architecture. Thus, chroot would not be successful.

The way to solve the problem is allow kernel automatically recognize the binary format and call certain emulation tool such as qemu to execute that binary. The way to do it is Kernel Support for miscellaneous Binary Formats. You need configure sysctl.conf and put qemu-ppc in sysroot/usr/bin/qemu-ppc-static

sysctl -a

fs.binfmt_misc.qemu-ppc64 = magic 7f454c4602020100000000000000000000020015
fs.binfmt_misc.qemu-ppc64 = mask fffffffffffffffffffffffffffffffffffeffff
fs.binfmt_misc.qemu-ppc = enabled
fs.binfmt_misc.qemu-ppc = interpreter /usr/bin/qemu-ppc-static
fs.binfmt_misc.qemu-ppc = flags:
fs.binfmt_misc.qemu-ppc = offset 0