[aklug] Re: Kernel 2.6.15 doesn't have core 2 support

From: Damien Hull <dhull@digitaloverload.net>
Date: Thu Jan 17 2008 - 11:10:35 AKST

Arthur Corliss wrote:
> On Wed, 16 Jan 2008, Damien Hull wrote:
>
>
>> Ubuntu Dapper has kernel 2.6.15. I installed the source package and ran
>> make menuconfig. Looking through the processor family section I don't
>> see anything on the core 2. It does have Xeon support.
>>
>
> The core 2 option in some kernel revs has nothing to do with SMP support, it
> only activates some core 2 specific optimizations, nothing more. Any
> generic SMP x86 kernel w/APIC enabled will show multiple processors.
>
> It was pointed out how to rebuild a 2.6 kernel from an existing, running
> kernel, but here's a cheat sheet:
>
> # Start from a clean kernel tree
> cd /usr/src/linux
> make mrproper
>
> # Import current kernel settings
> gzip -dc /proc/config.gz > .config
> # If /proc/config.gz isn't present it may have been built as a module,
> # so try 'modprobe configs'. If it works, it'll show up in /proc now.
> # If you still don't have /proc/config.gz, look for a config-??? in
> # /boot, your distro provider may have been kind enough to copy it
> # there as well. Copy it to ./.config
> yes "" | make oldconfig
>
> # Make any desired changes
> make menuconfig
>
> # Check to see if the distro has automated kernel installation
> which installkernel
> # If it's there, all that you should have to do is:
> make
> make modules_install
> make install
> # If it's not there, things get a bit more hairy, depending on the
> # use of initramfs, etc. At its simplest all that's needed is to copy
> # (on x86) arch/i386/boot/bzImage to /boot/vmlinuz, and reinstall your
> # bootloader (if using lilo -- grub doesn't require anything to be done).
> # The System.map file is optional, and only really needed to get some
> # readable kernel panic messages. But if you're system isn't dying
> # from a kernel panic, it's never used.
> # If you're using an initrd/initramfs you will need to update that image
> # to, at a minimum, update the kernel modules. initrds can be
> # decompressed and mounted via loopbacks to do so, initramfs are just
> # compressed cpio archives. Just extract and and recreate after updating.
>
> # If you want to make an installable package for your distro, some of the
> # following options may help
> make deb-pkg
> make binrpm-pkg
>
> Final notes: a lot of kernel options can be tweaked/enabled/disabled by
> kernel commands. You can see what your bootloader passed to your kernel
> when it was launched by 'cat /proc/cmdline'. Modifying your bootloader may
> be needed to undo those kind of overrides.
>
> Compiling kernels isn't deep magic or complicated, but it does take some
> knowledge of hardware and how it works together. If you know that much
> configuring a kernel can often be blindingly obvious.
>
> Looking at this thread I have to think that explaining the entire boot
> process, from system firmware to bootloader, to kernel, to init, is
> necessary to clear up some confusion. FNL, anyone?
>
> --Arthur Corliss
> Live Free or Die
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>
After thinking about it this morning I believe I figured out the
problem. I had to add the following to the kernel to get Dapper installed.

    * noapic
    * nolapic
    * noacpi
    * acpi=off

Once Dapper was installed I had to leave these option in there. When I
installed 2.6.23-14 the above option were also added in grub. With these
options /proc/cpuinfo showed only one processor. For some reason I
decided to take these options out. Once I did that I was able to get two
cores in /proc/cpuinfo.

This leads me to believe that kernel 2.6.15 might work with the core 2
duo. However, it won't work with my motherboard. Not unless I add noapic
etc...

Feel free to create me if I'm wrong.
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Received on Thu Jan 17 11:11:22 2008

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