lfs-book/chapter02/aboutsbus.xml

<sect1 id="ch02-aboutsbus">
<title>About SBUs</title>
<?dbhtml filename="aboutsbus.html" dir="chapter02"?>

<para>Most people would like to know beforehand how long it approximately
takes to compile and install each package. But "Linux from Scratch" is built
on so many different systems, it is not possible to give actual times that are
anywhere near accurate: the biggest package (Glibc) won't take more than
twenty minutes on the fastest systems, but will take something like three days
on the slowest -- no kidding. So instead of giving actual times, we've come up
with the idea of using the <emphasis>Static Binutils Unit</emphasis>
(abbreviated to <emphasis>SBU</emphasis>).</para>

<para>It works like this: the first package you compile in this book is the
statically linked Binutils in Chapter 5, and the time it takes to compile this
package is what we call the "Static Binutils Unit" or "SBU". All other compile
times will be expressed relative to this time.</para>

<para>For example, the time it takes to build the static version of GCC is 3.9
SBU. This means that if on your system it took 10 minutes to compile and
install the static Binutils, then you know it will take nearly 40 minutes to
build the static GCC. Fortunately, most build times are much shorter than the
one of Binutils.</para>

<para>Note that SBUs don't work well for SMP-based machines. But if you're so
lucky as to have multiple processors, chances are that your system is so fast
that you don't mind.</para>

</sect1>