# Pentium 4 Hyperthreading Problem

## BigDaveyL

I'm having a bit of a problem trying to boot into Gentoo.  My hardware is:

Dell 8300

2.8 GHz Pentium 4 with HyperThreading

512 MB RAM

120 GB SATA HD (Windows XP Professional only)

200 GB ATA/133 (Contains my partions for Gentoo)

Whenever I boot Gentoo from LILO, it will boot the kernel to a random point and then reboot itself, and put me back at the LILO prompt.  I was using vanilla-sources-2.6.12.5 and even tried changing to gentoo-sources-2.6.13-r3 with similar results.  I've tried booting with the 2004.3 LiveCD, similar results happen as well.  I have an SMP kernel compiled and the vanilla kernel I've been using has been working for awhile.  I do have HyperThreading enabled in the BIOS and Windows XP Professional does infact boot and see 2 processors.

However, when I disable HyperThreading in the BIOS, Gentoo boots fine.  Obviously, I'd like (more like want) HyperThreading to be enabled when I boot into Gentoo.

Thanks,

Dave

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## Janne Pikkarainen

At least with IBM servers (P4 Xeon) HT works flawlessly. Here are the kernel configuration snippets I consider important:

Processor Type and Features

---------------------------------

- Subarchitecture type: PC-compatible

- Processor family: Pentium 4 etc

- HPET timer support

- Symmetric multi-processing support

- SMT (hyper-threading scheduler support)

- MTRR (Memory Type Range Register) support

What is the "random point" you mentioned? Is kernel just getting its own act together or does it sometimes boot to the point where your Gentoo is actually starting some services and nearing the login prompt?

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## BigDaveyL

I believe all of those options are turned on.

I can't even get to the point where services start or even get to the login prompt.

vanilla-sources-2.6.12.5 - I can see the about PS/2 being loaded before it reboots

on the LiveCD - I can see messages about isapnp being loaded.

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## Janne Pikkarainen

Have you tried to pass any extra parameters to kernel when booting? If not, you better try them.  :Wink: 

Start with acpi=ht (which skips most of the ACPI support, enabling only the bits needed for HT). If that doesn't work, try with noapic, nolapic and pci=routeirq. Try them one of the time and in combinations, if any of them still doesn't work, you should read /usr/src/linux/Documentation/kernel-parameters.txt and see if any of them is any good for you.  :Smile:  Passing the parameters is easy, for example with the live-cd "linux acpi=ht" would try to boot with acpi=ht parameter. (could be that live-cd boots with "gentoo acpi=ht", can't remember... boot screen should tell it to you anyway)

Also updating motherboards BIOS is a good idea, if you're willing to take all the risks it involves.

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## BigDaveyL

I've tried several of those options mentioned in your post (some of which I tried before I posted).  Still doesn't work.

I'm running the latest BIOS from Dell for my model.  Maybe I'll try re-setting the BIOS back to the default settings and try to boot then.

The one really odd thing is this LiveCD has worked for awhile, and only now it is giving me trouble.

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## BigDaveyL

I've tried to reset the BIOS to the default settings.  Still doesnt work.

Anyone run across a similar problem?

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## frilled

No -- I have a Dimensio 8300, too, although it's equipped a 3.0 GHz P4.

Be sure to upgrade your BIOS to the latest version (I'm currently running A07). This box work *so* great. It's my favourite.

If you need specifics, PM me; I think I don't want to annoy averybody with a .config file.

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## wnelson

There was a change with 2.6.13-rc? that you have enable power management/ACPI to get hyperthreading to show up. This I believe is fixed with 2.6.14-rc4

Walt

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## BigDaveyL

Thanks for your tips, I've fiddled around this weekend, but still not working, even with kernels that have worked for months (if not longer).

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## zidour

I have run to the same problem recently... With HT computer just reboots itself at the beginning of the boot process. Without HT everything is fine. Did you find a solution?

As you said, the weirdest thing is that it also happens with kernels that worked flawlessly before... What happened?

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## BigDaveyL

Hey,

I think I've solved this or maybe it was just luck...

Check your connections in the back of your PC.  The USB cable that goes from the back of the computer was not plugged in all the way.  Seemed to work after that.

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## zidour

You are damn' right!

That's really strange. I unplugged all the cables and then plugged them back again and everything works fine.

Thanks!

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## BigDaveyL

I guess it puts some truth to "make sure everything is plugged in," eh?

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