In this, the term "PowerPC" normally refers to the Apple G3, G4 and G5 PowerPC machines. Other PowerPC based machines exist but this document and repository is primarily focused on the Apple PowerPC machines.
Normally the LFS_TGT value as set in Chapter 3 can be left as is for building LFS on the PowerPC. LFS_TGT would likely need changes if building for some of the other variants of the PPC architecture (e.g. the e500v2) but for building LFS on an Apple PowerPC machine, LFS_TGT does not need to be modified.
Normally, the PowerPC kernel can be built from the standard linux kernel version as is specified in the LFS book. There are a number of non Apple PowerPC boards that are also supported in the standard kernel code. However, building LFS on the various embedded PowerPC devices will likely require a hunt for the needed kernel source for that particular machine..
The yaboot bootloader is typically needed on Apple PowerPC machines. Building yaboot from source is very problematic and it is easier to simply obtain an already existing yaboot binary package and use it instead. The yaboot binary tarball within this repository was created by repackaging Debians yaboot binary package into a simple tarball.
U-boot is a bootloader commonly used in non-Apple PPC machines.
In this case, the u-boot tools will be needed and have to be built
and installed prior to building the kernel.
The Apple PowerPC machines use a different partitioning scheme than IA machines. Several additional tools (e.g. mac-fdisk, hfsutils, etc ) will need to be built.