Dual Core

Alexander E. Patrakov patrakov at gmail.com
Wed Apr 30 09:15:49 PDT 2008

Nicolas FRANCOIS wrote:

> I just bought a DualCore, and a friend of mine told me I should build a
> 64bits system. Is there any point in this ?

You won't be able to use some packages without multilib (which is, essentially, 
building two systems, 64-bit and 32-bit, instead of one).

Some of the affected packages are due to the fact that they use 32-bit Windows 
DLLs. The examples are are wine (obviously), mplayer (partially, but, for 
example, you won't be able to play any 5.1 wma files from 
http://www.lynnemusic.com/surround.html; this music is used only as an example 
of what won't play). Given that the version of ffmpeg in the BLFS book is 
ancient, the situation is even worse: no WMV3 (aka VC-1) support, and crashes on 
interlaced H.264 video (readily triggered by digital TV broadcasts in 
Yekaterinburg, Russia).

The other class of affected packages are those where the programmer made 
assumptions not valid for 64-bit systems. This kind of problems usually 
manifests itself at runtime as segfaults. Until recently, this applied to 

Until the BLFS team goes through all the packages and places appropriate 
warnings, it is not recommended to avoid x86-64 on a desktop computers with less 
than 4 GB of memory.

> I noticed while installing a
> base Debian (to start building LFS ;-) that the chosen kernel was the
> AMD64 flavor. Is this normal ? And what options should I enable in the
> kernel that are specific to this processor?

This won't work for LFS as a host at all, unless you figure out how to use the 
"linux32" command (and even then, I am not sure that there will be support). And 
for the options, please build the 32-bit kernel, you already know how to do it 
for Pentium4-class machines, it will "just work" with 32-bit userspace.

Alexander E. Patrakov

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