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The initrd directive in grub.cfg refers to an initramfs image
In `menuentry` blocks, the `initrd` directive must point to the location (relative to the `/boot` directory if it is on a separate partition) of the `initramfs` file corresponding to the same kernel version. This directive is called `initrd` because the previous tool which created initial RAM disk images, [command]#mkinitrd#, created what were known as `initrd` files. The `grub.cfg` directive remains `initrd` to maintain compatibility with other tools. The file-naming convention of systems using the [command]#dracut# utility to create the initial RAM disk image is `initramfs-_kernel_version_.img`.
For information on using [application]*Dracut*, refer to xref:kernel-module-driver-configuration/Manually_Upgrading_the_Kernel.adoc#sec-Verifying_the_Initial_RAM_Disk_Image[Verifying the Initial RAM Disk Image].
After installing a new kernel with [command]#rpm#, verify that `/boot/grub2/grub.cfg` is correct and reboot the computer into the new kernel. Ensure your hardware is detected by watching the boot process output. If GRUB 2 presents an error and is unable to boot into the new kernel, it is often easiest to try to boot into an alternative or older kernel so that you can fix the problem. Alternatively, use the boot media you created earlier to boot the system.
Causing the GRUB 2 boot menu to display
If you set the [option]`GRUB_TIMEOUT` option in the `/etc/default/grub` file to 0, GRUB 2 will not display its list of bootable kernels when the system starts up. In order to display this list when booting, press and hold any alphanumeric key while and immediately after BIOS information is displayed, and GRUB 2 will present you with the GRUB menu.
Configuring the OS/400 Boot Loader
indexterm:[OS/400 boot loader,configuring]indexterm:[OS/400 boot loader,configuration file] The `/boot/vmlinitrd-_kernel-version_pass:attributes[{blank}]` file is installed when you upgrade the kernel. However, you must use the [command]#dd# command to configure the system to boot the new kernel.
As `root`, issue the command [command]#cat /proc/iSeries/mf/side# to determine the default side (either A, B, or C).
As `root`, issue the following command, where _kernel-version_ is the version of the new kernel and _side_ is the side from the previous command:
[command]#dd if=/boot/vmlinitrd-_kernel-version_ of=/proc/iSeries/mf/pass:attributes[{blank}]_side_pass:attributes[{blank}]/vmlinux bs=8k#
Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly.
Configuring the YABOOT Boot Loader
IBM eServer System p uses YABOOT as its boot loader. YABOOT uses `/etc/aboot.conf` as its configuration file. Confirm that the file contains an `image` section with the same version as the [package]*kernel* package just installed, and likewise for the `initramfs` image:
boot=/dev/sda1 init-message=Welcome to {MAJOROS}! Hit <TAB> for boot options
partition=2 timeout=30 install=/usr/lib/yaboot/yaboot delay=10 nonvram
Notice that the default is not set to the new kernel. The kernel in the first image is booted by default. To change the default kernel to boot either move its image stanza so that it is the first one listed or add the directive `default` and set it to the `label` of the image stanza that contains the new kernel.
Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly.