I spend most my time in the "arm" world and have been slacking when it comes to aarch64 (arm64) the reason for this is there is no hardware "in the wild" to support it but there some promising candidates been released in Q2 + (http://www.anandtech.com/show/7724/it-begins-amd-announces-its-first-arm-based-server-soc-64bit8core-opteron-a1100) so im getting back upto date.
im taking up bruce's "challenge" to do a "hint" on a "hybrid" cross build the idea is as follows. 1)Build "cross" binutils 2)Build "gcc/glibc" 3)implement a "sysroot" 4)create a emulation path /usr/gnemul/qemu-* mount all libdirs using --bind to a path in sysroot /opt/*/lib /lib /usr/lib .... 5)then copy into the sysroot the "host" toolchain and libs in a "multilibpath" this will allow executing the host not cross binaries in the sysroot this allows using a cross compiler in a "native" enviroment 6)using qemu [static] copied to the sysroot and setting up binfmt_misc you can chroot to the sysroot run the hosts "bash" and the "gcc" will be the cross compiler as with the cross binutils all running x86_64 7)running any "native" binaries will be run under the emulator ie uname -a will give appropriate results for the target. doing it this way you are able to build as many packages "cross" as possible and for more tricky ones can chroot into the sysroot and build the source as if it was native using host tools and libs while in the "target" chroot problem children are python / perl and gnome bits that use introspection [python]. you need to make sure that the toolchain packages are not rebuilt and installed in the sysroot use of a staging area and some form of packaging is needed cpio/tarball/rpm [this evil i speak of] the idea is to build a full system and be able to install it onto a harddrive and run it on the target. this is very different from using a "emulator" ie qemu-system-* as they are really slow and inefficient. this is the method i use to build most the time its not LFS and close but not quite CLFS the packages from BLFS are mostly out the box and work fine even when chrooting to the target under qemu the same applies. the aim is to sync with as much as xLFS as possible. im working through a aarch64 build currently and will be putting this together as i go. i feel this falls into the "education" mandate of LFS allowing experimentation with the other kids on the block. qemu will need to be bumped to 1.8.0 [when it is released to support aarch AKA arm64]. im not sure where to put the binfmt bits /etc/binfmt.d/*.conf seems to be common and is suited for bootscripts i seem to recall some support in systemd too. comments / complaints are welcome. Greg -- http://linuxfromscratch.org/mailman/listinfo/blfs-dev FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page
