Porting to new hardware

Tonglebeak · Guru Joined: 23 Mar 2006 Posts: 362

I'm going to be recompiling everything (fresh install) for new hardware (new cpu, mobo, etc). I'd like to keep my current conf files, as well as the current packages I have. What is the best way of doing this? Copying the world file and all of /etc? I'd like to keep my kernel as similar as possible as well. Would a make oldconfig with the current config, and then selecting the appropriate hardware, suffice for this? Thanks.

pappy_mcfae · Posted: Fri Jan 14, 2011 8:37 am Post subject:

All of this assumes you are going from x86 to x86, or x86_64 to x86_64. If you are trying to go from x86 to x86_64, or the other way, that requires a completely new setup.

Assuming you're not moving from 32 to 64 bit, or vice versa:

1. Start by adapting your kernel to your new machine's hardware. In most cases, this is a quick and easy affair.
2. Make any required changes (USE flags, etc) in /etc/make.conf.
3. Rebuild the toolchain with emerge -aev system --keep-going.
4. Rebuild everything with emerge -aev world --keep-going.

If your new system can boot to some degree of functionality; bonus! If not, you'll have to use a boot CD. That should get you where you need to be, as well as giving your system a good initial burn-in/workout.

Cheers,
Pappy
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BitJam · Posted: Sat Jan 15, 2011 3:05 am Post subject:

I've migrated to a different mobo by simply copying the entire file system and then rebuilding the kernel after adding config options for the new hardware. I don't see why you would have to rebuild the tool chain as long as the processor is the same. ISTM that is the essence of the Linux kernel/user-land design. The kernel deals with the hardware in a standard way so user-land programs don't have to worry about it.

pappy_mcfae · Posted: Sat Jan 15, 2011 9:47 am Post subject:

When someone says, "new cpu, mobo, etc" that means they *should* really redo everything so that their software is tuned for the new system. I've done it more than once.

Kernel reconfiguration is an absolute must. If a kernel is properly configured, it is set only for the machine on which it resides. That means a new chip and mobo (with new devices) requires a reconfigured kernel...at least if you want your performance to be up to what your new machine can do.

And then there's stability. Since the idea of Gentoo is to tune your OS to your computer, thus giving you great stability, changing the computer means retuning the OS for the new machine. It's not an absolute must, but if you want to know your system is as stable as possible, it comes as close to a must as can be.

Cheers,
Pappy
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BitJam · Posted: Sat Jan 15, 2011 10:07 am Post subject:

I completely agree with you that reconfiguring the kernel is often required. My point is that I see absolutely no reason to rebuild the tool chain (assuming you are using the same type of CPU). It gains you nothing. How on earth could changing the mobo (and not the CPU type) affect the stability or optimization of the tool chain?

When I did it, I needed to add drivers to the kernel for a different ethernet controller and a different SATA controller. I just don't see how any of that stuff would have the slightest affect on the user-land tool chain.

pappy_mcfae · Posted: Sat Jan 15, 2011 10:10 am Post subject:

The reasons are many. If nothing else, redoing everything is a good test of the system. It's not like it's going to hurt anything or kill the system to recompile everything. And...if it does, now's the time to know.

Cheers,
Pappy
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