Change from P II to P III Dual, possible?

[Gymnae]

Hi,

I love to register on a Forum just to ask for help, don't you too?

However, I suffer the following scenario:
a) I'm a Gentoo Noob
b) I bought a new Motherboard for my little Gentoo 2005.0 Server which has two Pentium III 450 MHz CPUs.
Currently, some freak Siemens-Nixdorf Mainboard is working in there, bundled with a Pentium II.
My Gentoo Installtion was a lot of work an I have it configured just the way I love it. I would never make it that good again...I guess...
I would love to hear, that I just cramp the new MoBo in, change some Use Flags (how was that done again?) and recompile.

What I look for:
- Which USE Flags do I have to set for fully benefting from the Dual CPUs
- Is it possible to update the system to 2005.1 while at
- what to tell portage to update with the new use flags...
- and: how high are the chances that the system will boot up anyway after i build in the new MoBo
(only CPU, RAM, Motherboard are being changed)

Thanx for any hints!

[Cpt_McLane]

a lot of questions... some answers:

[Gymnae]

Thank you very much for your quick answer.

Would it be advisible to change the kernel config prior to changing the cpu(s)?

How can I find out, which Use Flags would make sense for a P III Dual System, are there any lists
that tell me what specific instructions such a CPU can handle (that the P II couldn't)?

again, thanx!

[Cpt_McLane]

i had a "normal" Pentium 4 when i set up my gentoo in 2004... in august 2005 i upgradet to a p4 HT cpu with a new mainboard and new ram, so i assume it's a simmilar situation...
my windows installation went out with a bluescreen while booting (that's why i'm using linux only at the moment, never needed windows since then) but gentoo linux was able to start. even though it just had one proc active, i just activated multi proc support in kernel, recompiled it and rebootet the new kernel... then i re emerged nvidia-kernel and since then i'm running a (in my oppinion) stable gentoo..

summary:
there is no need for changing the use-flags... just the kernel and depending packages like nvidia have to be recompiled but the box should be able to boot as long as you upgrade and stay in the vendor line (no changing from intel to amd or otherway)...
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[Gymnae]

cool cool, thanx!

I will add one use flag: SSE and therfore do a

[Tommy Vercetti]

If you're swapping the hd from the P2 to the P3, do enable all P3's hardware in the kernel config, prior to the moving of the hd, or else it won't boot.
If you use genkernel, you won't probably have any headache.

For changing USE flags, you can use ufed.
Simply: emerge ufed
ufed on your console and you're gonna have 1+ hour of fun with it

I recommend that you change your USE flags prior to updating to 2005.1, since this will avoid re-recompiling some packages.

For going to 2005.1, simply:
emerge --sync && emerge -uDN world
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[Bob P]

[Gymnae]

Thanx for all the answers!

So what I'm going to do is:
a) Backup
b) Build a new Kernel & copy it over
c) Shutdown & Build in sweet new Hardware
d) Use the new Kernel
e) emerge --sync && emerge -uDN world
e) emerge ufed



I'll tell ya if all worked fine.

The idea of building the Kernel from a Live CD ain't that good, as I don't have an
optical Drive connected to the PC all the time.

greets,
gymnae

[Tommy Vercetti]

I sugest that you first emerge ufed and use it, and then emerge sync and emerge -uDN world, since if you modify the USE flags after updating, you're much probably gonna have to recompile a bunch of packages again
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ASUS A8V Deluxe
1GB Corsair Dual Channel
ATI Radeon 9600 XT 128MB Gigabyte 500/600
120GB Maxtor
200GB WD

[Bob P]

i wouldn't emerge a bunch of new packages unless you just want to tempt fate. when you're trying to move a production server from one hardware platform to another, the wisest thing to do is to change as little as possible on the system, and change ONLY what is necessary.

all of the P2 code that's on your server will run fine on the P3. the only thing that you should change before you migrate is the KERNEL. don't change anything else. by changing the kernel you will be able to enable SMP and build appropriate hardware recognition into your system. you can even enable P3-specific code at the kernel level. but DON'T recompile your entire system!

if you rebuild everything, how would you isolate the problem if something broke? to make the transition to the new box easiest, and to make troubleshooting easier, only change the kernel. then move the HD to the other box. get the box up and running. if it fails to work, you know EXACTLY where the problem lies. only AFTER you've solved that problem should you consider updating any of the code. somebody would have to feel awfully LUCKY to try to take all of these steps at once. its much safer to isolate each step.

practically speaking, you don't even need to build architecture-specific code for your servers. you could just build all of your boxes for the lowest common denominator hardware platform that you have in-house. then all of the HDs will be interchangeable, and to move from box to box the MOST that you would have to do is build a kernel.

people who don't know better tend to overrate the processor-specific code on gentoo. how badly do you need the specific code features that are present in a P3 but not in a P2 on a SERVER? the answer to that question is very different than it is on a DESKTOP, so take the time to answer it before wasting alot of time rebuilding a system for a marginal putative gain.

just my $0.02

[Gymnae]

Wow, thanx for your long postings, I will reconsider recompiling all code.
Honestly, I don't know how much the Software woule benefit the new CPU specifig Instructions, i.e. SSE.
SMP may very well be the most important change, and correct, as it is done on a Kernel base, I wouldn't
need to go through all the trouble of recompiling.
The only thing is: I haven't updated my system in a long time, so security updates, even those, would
ask for an emerge -world.

We'll see, I first just compile a new Kernel and check the perfomance increase. If I'll be happy with that, I won't recomple with new USE Flags at all. Otherwise, well, I'll take my best shot....


greets,
gymnae

[Gymnae]

Hi,

now I recompiled, or tried to recompile the Kernel, only changing the Parameters from
Processor Family P II to P III and enabled SMP.
Now, if I run the make && make modules_install I get:

[comprookie2000]

What do you think is wrong with it?
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[Gymnae]

[j-m]

[duby2291]

Ignore these guys.

[j-m]

[linuxtuxhellsinki]

Thanks j-m First time I bothered to read depmod & modules.dep man-pages, and looked inside /lib/modules/2.6.12-gentoo-r10/modules.dep file and understanded what it means.

It's sometimes much better to point people to right direction and let 'em read & learn by them selves. It's much more teaching than just telling the right solution.
But of course things could also be so complex that U can't just point like 'check from man bash'
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