Installing new 64bit kernel on AMD64, question?

[Joncamp]

I have red had linux 32 bit, 2.6 kernel, wish to setup my new amd64 with 64bit Linux.

(1) Can I install 32 bit linux, then install a new 64 bit kernel?
(2) Do I have to re-compile all software I run with 64 bit c++ switches?
(3) Do the 64 bit distributions of say Ubuntu come with all 64 bit compiled software?

Thanks.
jon

[dkeav]

1) no
2) no
3) no, not all some closed source things mostly multimedia related, ie flash, win32codecs ect ect still can only be distributed as a 32-bit binary, but these distros take advanted of a multi-lib install so running 32-bit binaries is no problem

[bwkaz]

(1) Can I install 32 bit linux, then install a new 64 bit kernel? You can, but you don't have to. I did exactly this when I got a 64-bit processor; my existing LFS system was 32-bit only, so I followed the CLFS book, and where I had to choose whether to chroot or reboot, I compiled the kernel as if I was going to reboot, then booted to it (all my 32-bit processes still ran, because I turned on ELF32 compatibility support when configuring the kernel), and did the chroot method.

So I know it's possible. However, it's a large pain, and you have to remember to provide a cross-compiler to the kernel build, and set ARCH (every time you recompile the kernel). It'd be much easier to just install a 64-bit distro and go from there. ;) (Then you can use the native compiler when building the kernel.)