Why is glibc built again in chapter 6.9?

Unturned3 · 06-21-2018, 03:38 PM

Hello,
I'm following the LFS book version 8.2 and I am confused about the way that glibc is built and installed.
Why is glibc re-compiled and installed in chapter 6.9? Isn't it already cross-compiled by the GCC and Binutils built in Pass 1 (chapter 5)?
Thanks!

spiky0011 · 06-22-2018, 02:44 AM

All packages in ch5 were built into a temp toolcahain "dir /tools" this will be discared so now ch6 builds the actual system to the LFS partition, The toolchain is built so we can build the proper system without Touching the host system.

RoLoR · 06-22-2018, 09:58 AM

Indeed Chapter 5 is to make a building independent of host. If you copy version-check.sh to the $LFS/sources you can see how and when parts are taken over from host by running it with

Code:

bash version-check.sh

after every little step you make in chapter 5.
Chapter 6 is the actual build of LFS as said by spiky0011

Unturned3 · 06-22-2018, 12:07 PM

Ahh, I see, so all the tools built in chapter 5 are for constructing a temporary & host-independent toolchain that can be used to build other packages in ch6.
But still I find the "Toolchain Technical Notes" section in ch5 quite confusing. At which point does the tools compiled become host-independent? If I use my host compiler to compile a new gcc & bintuils package, and then use the new tools to compile glibc, how is the glibc built here host-independent?
Sorry if this is a silly question; I am quite inexperienced in complicated compiling tasks.
BTW are there any good tutorials/guides on compiling software?

Thanks a lot!

spiky0011 · 06-22-2018, 12:55 PM

In ch6 chroot your path changes and puts tools last in where it looks "/bin:/usr/bin:/sbin:/usr/sbin:/tools/bin".
Also if you look at where stuff is being installed to, ch5 prefix=/tools, now in ch6 prefix=/usr, then in ch-6.10 things get moved and linked. So then you start by looking at dirs on the partition.

Compiling software is prety much like what you are doing now, yes there are otherways which you will come across later in LFS and then more so in BLFS. If and when you go outside the book, packages have README and INSTALL files in them that you can read.