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

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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Received on Wed Jan 16 21:41:21 2008