RHEL5 Kernel HOWTO

(Redirected from Downgrade OpenVZ)

This is the approved revision of this page, as well as being the most recent.

Introduction

This HOWTO will show you how to get a RHEL5-based OpenVZ kernel running on a Funtoo Linux system.

Step 1: Downgrade sys-fs/udev (package not on wiki - please add), sys-fs/lvm2 (package not on wiki - please add)

Downgrade udev to a version compatible with kernels previous than 2.6.27:

# echo ">=sys-fs/udev-147" >> /etc/portage/package.mask
# emerge -u udev

This will also require a downgrade of lvm2, if you are using it. Version 2.02.68 is a good one to use:

# echo ">=sys-fs/lvm2-2.02.69" >> /etc/portage/package.mask
# emerge -u lvm2

Downgrade make to a version compatible with older kernel version:

# echo ">=sys-devel/make-3.82" > /etc/portage/package.mask
# emerge -u make

Step 2: Install binary kernel

The process for installing an RHEL5-based kernel with OpenVZ support has been drastically simplified. Simply perform the following steps:

# echo "sys-kernel/openvz-rhel5-stable binary" >> /etc/portage/package.use

This will result in the kernel sources and a binary kernel and initrd being merged. Without binary in USE, only the sources will be merged. Then:

# emerge openvz-rhel5-stable

This will build and install a binary kernel image and initial RAM disk, and take care of installing all necessary dependencies like gcc-4.1.2. Once the binary kernel image and initrd is installed, configure /etc/boot.conf to find and boot the new kernel.

Note: you may need to temporarily modify your CFLAGS settings to ensure they are compatible with gcc-4.1 systems. In particular, -march=native is not recognized by the older gcc.

[1] http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/i386-and-x86_002d64-Options.html#i386-and-x86_002d64-Options

Step 3: Enable vz initscript

When your system boots with OpenVZ support enabled, it will require /etc/init.d/vz to run:

# rc-update add vz default

Step 4: Edit boot.conf

Update /etc/boot.conf to point to your new kernel, ie:


boot {
        generate grub
        default kernel-openvz-rhel5-stable-x86_64-2.6.18-028stab089.1
        timeout 3
}

"Funtoo Linux with OpenVZ" {
        kernel kernel-openvz[-v]
        initrd initramfs-openvz[-v]
        params += real_root=auto
}

Note that you must use the:

params += real_root=auto
option. This will automatically configure your boot loader to specify your root file system as the
real_root

to the initrd.

Step 5: boot-update

Now, simply run boot-update as root:

# boot-update

boot-update should show the new kernel as being found and display it as the default selection for the next boot. You can now reboot your system and start using OpenVZ.