Re: Best way to proceed for a 64-bits version of Knoppix?
On Tue, Jun 28, 2011 at 1:54 AM, Capri Corny <capricornyx@gmail.com> wrote:
> I explicitly stated that 32 vs 64 bits was not the subject here.
> Furthermore, it will not be difficult to deliver both 32 and 64 bits in the
> same package, just two different compressed images to choose between,
> analogous to the way we can choose between 32 and 64 bits kernels when
> booting Knoppix today. From my own very modest and superficial testing of
> 32 vs "pure" 64 bits on ordinary actual hardware (like the I5-430M
> processor), the difference is not huge today with ordinary user space
> programs.
>
> So making this an important development issue today isn't very fruitful, I
> think.
> There is, however, no good reason why Knoppix should be confined to 32-bits,
> if volunteers take the (mostly administrative) job of making a 64-bits
> version for each release. Remastering-wise, 32 and 64 bits versions should
> behave similarly.
>
> As for the approach, I think I may try out starting from a basic 64-bits
> Debian and see how it works out.
Finnix (loosely based on the basic structure of Knoppix as of 2005,
but diverged greatly since then) recently completely rearranged the CD
layout, with one of the goals being exactly this. For a long time,
Finnix has included both 32 and 64 bit kernels, but only a 32 bit
userland. Today it is the same, but with the structural changes as of
Finnix 101, it could theoretically support both 32 and 64 bit
userlands in the the future (or via a remaster).
In a nutshell, there is a file called /finnix/arch.map on the CD. It
looks like this:
# This is the architecture map for Finnix. It is used to map the
# output of "uname -m" to an architecture group for mounting userlands.
# In the case of 64-bit architectures, the primary architecture group
# is tried first, and if it doesn't exist, the fallback group is tried.
#
# uname arch_group arch_fallback_group
i386 x86
i486 x86
i586 x86
i686 x86
x86_64 amd64 x86
ppc ppc
powerpc ppc
ppc64 ppc64 ppc
powerpc64 ppc64 ppc
And the 32 bit compressed root is located at
/finnix/arch/x86/root.img. Whenever Finnix boots today, it parses
arch.map, and if it's booted into an x86_64 kernel, it first looks for
/finnix/arch/amd64/root.img. If that doesn't exist, it moves on to
try /finnix/arch/x86/root.img. So if Finnix were to have a 64 bit
userland in the future, it would be pretty easy to integrate.
I imagine a similar setup could be used for Knoppix.
RF
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