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= GRUB 2
'''
[IMPORTANT]
======
This page was automatically converted from https://fedoraproject.org/wiki/GRUB_2
It is probably
* Badly formatted
* Missing graphics and tables that do not convert well from mediawiki
* Out-of-date
* In need of other love
Please fix it, remove this notice, and then add to `_topic_map.yml`
Pull requests accepted at https://pagure.io/fedora-docs/quick-docs
Once that is live, go to the original wiki page and add an `{{old}}`
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....
{{admon/note|This page has a new home!|
This wiki page is no longer maintained. Please find the up-to-date
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}}
....
======
'''
= The GRUB2 Bootloader
[[introduction]]
Introduction
------------
GRUB 2 is the latest version of GNU GRUB, the GRand Unified Bootloader.
== Introduction
*GRUB2* is the latest version of *GNU GRUB*, the _GRand Unified Bootloader_.
A bootloader is the first software program that runs when a computer
starts. It is responsible for loading and transferring control to the
operating system kernel, (Linux, in the case of Fedora). The kernel, in
turn, initializes the rest of the operating system.
operating system kernel. In Fedora, the kernel is Linux. The kernel then initializes
the rest of the operating system.
GRUB 2 has replaced what was formerly known as GRUB (i.e. version 0.9x),
which has, in turn, become GRUB Legacy.
*GRUB2* is the follower of the previous version *GRUB* (version 0.9x). The original version is available under the name *GRUB Legacy*.
Starting with Fedora 16, GRUB 2 is the default bootloader on x86 BIOS
systems. For upgrades of BIOS systems the default is also to install
GRUB 2, but you can opt to skip bootloader configuration entirely.
Since Fedora 16, *GRUB2* has been the default bootloader on x86 BIOS
systems. For upgrades of BIOS systems, the default is also to install
*GRUB2*, but you can opt to skip bootloader configuration entirely.
[[tasks-common-issues]]
Tasks / Common issues
---------------------
[[installing-grub-2-on-a-bios-system]]
== Installing GRUB2 on a BIOS system
[[updating-grub-2-configuration-on-bios-systems]]
Updating GRUB 2 configuration on BIOS systems
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Usually, *GRUB2* will be installed by the installer, *Anaconda*, during the installation process. You will probably never have to deal with manual installation of *GRUB2*. However, in certain situations , you will want to install *GRUB2* manually, if you want to update from an older or different bootloader, for instance. To install *GRUB2*:
The grub2 packages contain commands for installing a bootloader and for
creating a bootloader configuration file.
. Install *GRUB2* software using the *dnf* package manager
+
----
$ sudo dnf install grub2
----
grub2-install will install the bootloader - usually in the MBR, in free
unpartioned space, and as files in /boot. The bootloader is installed
with something like:
[[Installing-grub-2-on-the-hard-disk-bios]]
== Installing GRUB2 on the hard disk on BIOS systems
....
grub2-install /dev/sda
....
Installing the *GRUB2* software on your system does not change your bootloader configuration. In order to use *GRUB2* for loading the operating system, you have to install it on the hard disk. There are two possible options to install it:
grub2-mkconfig will create a new configuration based on the currently
running system, what is found in /boot, what is set in
/etc/default/grub, and the customizable scripts in /etc/grub.d/ . A new
configuration file is created with:
. in the master boot record (MBR) of the hard disk
. on an extra partition on the hard disk
....
grub2-mkconfig -o /boot/grub2/grub.cfg
....
*GRUB2* is able to load many operating systems, including Windows, so it is recommended to install it as the default bootloader in the MBR of the primary hard disk, usually the `sda` device.
The configuration format has evolved over time, and a new configuration
.Before you start
* Make sure you have installed the *GRUB2* software onto your system. See xref:installing-grub-2-on-a-system[Installing GRUB2 on your system] for more information.
* To automatically collect information about your disks and operating systems installed on them, the `os-prober` package needs to be installed on your system.
.Procedure
. List devices available on the system.
+
----
$ lsblk
----
. Identify the primary hard disk. Usually, it is the `sda` device.
. Install *GRUB2* in the MBR of the primary hard disk.
+
----
$ sudo grub2-install /dev/sda
----
. Create a configuration file for *GRUB2*.
+
----
$ sudo grub2-mkconfig -o /boot/grub2/grub.cfg
----
.More information
* The `grub2-mkconfig` command will create a new configuration based on the currently
running system. It collects information from the `/boot` partition (or directory), from the `/etc/default/grub` file, and the customizable scripts in `/etc/grub.d/`.
* The configuration format has evolved over time, and a new configuration
file might be slightly incompatible with the old bootloader. It is
therefore a good idea to first run grub2-install whenever you would need
to run grub2-mkconfig.
The Fedora installer, anaconda, will run these grub2 commands and there
is usually no reason to run them manually.
It is generally safe to directly edit /boot/grub2/grub.cfg in Fedora.
Grubby in Fedora patches the configuration when a kernel update is
therefore a good idea to first run `grub2-install` whenever you would need
to run `grub2-mkconfig`.
* It is generally safe to directly edit `/boot/grub2/grub.cfg` in Fedora.
*Grubby* in Fedora patches the configuration when a kernel update is
performed and will try to not make any other changes than what is
necessary. (Other distributions, in particular Debian and Debian-derived
distributions provide a software patch that adds an command which is
neither included nor needed in Fedora.) Manual changes might however be
overwritten with grub2-mkconfig next time the system is upgraded with
anaconda. Some customizations can be placed in /etc/grub.d/40_custom or
/boot/grub2/custom.cfg and will survive running grub2-mkconfig.
necessary. Manual changes might however be
overwritten with `grub2-mkconfig` next time the system is upgraded with
*Anaconda*. Customizations can be placed in `/etc/grub.d/40_custom` or
`/boot/grub2/custom.cfg` files and will survive running the `grub2-mkconfig` command.
[[updating-grub-2-configuration-on-uefi-systems]]
Updating GRUB 2 configuration on UEFI systems
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[[installing-grub-2-configuration-on-uefi-system]]
== Installing GRUB2 on a UEFI system
To install or fix GRUB 2 on a UEFI system on Fedora 18 or newer, you
need to do four things:
To install or fix *GRUB2* on a UEFI system on Fedora 18 or newer, you
need to do three things:
* create an EFI System Partition (ESP)
* install the bootloader files
* configure the *GRUB2* configuration
[[create-an-esp]]
Create an ESP
^^^^^^^^^^^^^
=== Create an ESP
UEFI firmware, in general, likes to boot from an EFI System Partition on
a disk with a GPT label. In `gdisk`, it looks something like this:
UEFI firmware, in general, likes to boot from an _EFI System Partition_ on
a disk with a GPT label.
....
Number Start (sector) End (sector) Size Code Name
1 2048 264191 128.0 MiB EF00 EFI System
....
.Before you start
That partition should be formatted as FAT. If in doubt, FAT32 is a good
dialect of FAT to choose.
. Learn how to create partitions using `gdisk`.
.Procedure
. List available block devices to find a place to create your ESP.
+
----
$ lsblk
----
. Create at least a 128 MiB disk partition using a GPT label on the primary hard disk.
+
----
$ sudo gdisk /dev/sda
----
. Format the partition with the _FAT32_ file system.
+
----
$ sudo mkfs.vfat /dev/sda1
----
. Mount the partition to `/boot/efi` mount point.
+
----
$ sudo mount /dev/sda1 /boot/efi
----
Fedora expects this partition to be mounted at `/boot/efi`.
[[install-the-bootloader-files]]
Install the bootloader files
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
=== Install the bootloader files
If you don't already have the relevant packages installed, do for Fedora
22 and later versions with link:dnf[DNF] or with YUM for older Fedora
releases:
In order to use *GRUB2* with on the UEFI systems, you need to install appropriate packages:
....
.Before you start
. Mount the `/boot/efi` mount point. See xref:create-an-esp[Create an ESP] to create it.
.Procedure
. Install the necessary packages.
+
----
dnf install grub2-efi grub2-efi-modules shim
yum install grub2-efi grub2-efi-modules shim
....
----
If you do, then try:
....
. If they are already installed, reinstall them.
+
----
dnf reinstall grub2-efi grub2-efi-modules shim
yum reinstall grub2-efi grub2-efi-modules shim
....
----
instead.
.More information
Make sure that /boot/efi is mounted when you do this.
This installs the signed shim and the GRUB 2 binary.
* This installs the signed shim and the *GRUB2* binary.
[[create-a-grub-2-configuration]]
Create a GRUB 2 configuration
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
=== Create a GRUB2 configuration
Under EFI, GRUB 2 looks for its configuration in
Under EFI, *GRUB2* looks for its configuration in
`/boot/efi/EFI/fedora/grub.cfg`. For newly installed kernels to work,
`grubby` expects `/etc/grub2-efi.cfg` to be a symlink to the real
grub.cfg (i.e. `/boot/efi/EFI/fedora/grub.cfg`).
grub.cfg (for example `/boot/efi/EFI/fedora/grub.cfg`).
If you already have a grub 2 EFI config file, you should be okay. If
not, grub2-mkconfig can help, but your mileage may vary.
If you already have a *GRUB2* EFI config file, you do not need to do anything else. Otherwise, you can try to create the configuration file using the `grub2-mkconfig` command.
`   grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg`
----
$ sudo grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
----
[[create-a-boot-menu-entry]]
Create a boot menu entry
^^^^^^^^^^^^^^^^^^^^^^^^
[[solve-problems-with-uefi-bootloader]]
=== Solve problems with UEFI bootloader.
TL;DR: This should happen automatically. If it doesn't, read on.
[[adding-the-boot-menu-entries]]
==== Adding the boot menu entries
When you power on your system, your firmware will look for EFI variables
that tell it how to boot. If you're already booted in EFI mode and EFI
that tell it how to boot. If you are already booted in EFI mode and EFI
runtime services are working correctly, you can configure your boot menu
with `efibootmgr`. If not, you'll have to bootstrap the process.
with `efibootmgr`. If not, you will have to bootstrap the process.
Fortunately, `shim` can help you bootstrap. The EFI program
`/boot/efi/EFI/BOOT/fallback.efi` will look for files called `BOOT.CSV`
in your ESP and will add boot entries corresponding to them, *if such
entries do not already appear to exist*. `shim` provides a `BOOT.CSV`
file that will add an entry for `grub2-efi` for you. So just using the
EFI Shell to invoke `fallback.efi` should do the trick. You can do this
in your ESP and will add boot entries corresponding to them. The `shim` command
provides a `BOOT.CSV` file that will add an entry for `grub2-efi` for you.
Using the *EFI Shell* to invoke `fallback.efi` should work for you. You can do this
with commands like:
....
----
> fs0:
> cd EFI\BOOT
> fallback.efi
....
----
If you have no boot entries at all, then just booting off your disk in
UEFI mode should automatically invoke `/boot/efi/EFI/BOOT/BOOTX64.EFI`,
@ -193,285 +199,357 @@ If you already have incorrect boot entries, you'll either need to delete
them or to modify `BOOT.CSV` to create new entries with different names.
[[adding-other-operating-systems-to-the-grub-2-menu]]
Adding Other operating systems to the GRUB 2 menu
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
==== Adding Other operating systems to the *GRUB2* menu
grub2-mkconfig will add entries for other operating systems it can find.
That will be done based on the output of the os-prober tool.
The `grub2-mkconfig` command will add entries for all operating systems it can find.
For the command to work, you have to have installed the *os-prober* tool that is provided by the `os-prober` package.
That might however not work so well, especially not for booting other
Linux operating systems, and especially not on UEFI systems. See
http://www.gnu.org/software/grub/manual/grub.html#Multi_002dboot-manual-config
.
Unfortunately, problem sometimes can appear. See the link:http://www.gnu.org/software/grub/manual/grub.html#Multi_002dboot-manual-config[GRUB manual] to solve issues with booting secondary operating systems.
[[setting-default-entry]]
Setting default entry
~~~~~~~~~~~~~~~~~~~~~
==== Setting default entry
Due to `grub2-mkconfig` (and os-prober) we cannot predict the order of
Due to `grub2-mkconfig` (and *os-prober*) we cannot predict the order of
the entries in `/boot/grub2/grub.cfg`, so we set the default by
name/title instead.
Open `/etc/default/grub` and ensure this line exists:
.Before you start
....
. Open `/etc/default/grub` and make sure these lines exist in the file.
+
----
GRUB_DEFAULT=saved
....
and ensure this line not exists:
....
GRUB_SAVEDEFAULT=true
....
or ensure this line exists:
....
GRUB_SAVEDEFAULT=false
....
----
Apply the change to `grub.cfg` by running:
. Apply the changes to `grub.cfg` by running.
+
----
$sudo grub2-mkconfig -o /boot/grub2/grub.cfg
----
....
grub2-mkconfig -o /boot/grub2/grub.cfg
....
.Procedure
Now list all possible menu entries
. List all possible menu entries.
+
----
$sudo grep -P "submenu|^menuentry" /boot/grub2/grub.cfg | cut -d "'" -f2
----
....
grep -P "submenu|^menuentry" /boot/grub2/grub.cfg | cut -d "'" -f2
....
. Set the desired default menu entry
+
----
$sudo grub2-set-default "<submenu title><menu entry title>"
----
Now set the desired default menu entry
. Verify the default menu entry
+
----
$sudo grub2-editenv list
----
....
grub2-set-default "<submenu title><menu entry title>"
....
.More information
If you understand the risks involved, you can manually modify the
`/boot/grub2/grub.cfg` file. In that case, set the number of the default operating system using the `set default` variable.
Verify the default menu entry
....
grub2-editenv list
....
If you understand the risks involved and still want to directly modify
/boot/grub2/grub.cfg, here's how you can do it:
Edit /boot/grub2/grub.cfg, and change the line
....
set default="0"
....
to
....
For example:
----
set default="5"
....
----
[[encountering-the-dreaded-grub-2-boot-prompt]]
Encountering the dreaded GRUB 2 boot prompt
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If improperly configured, GRUB 2 may fail to load and subsequently drop
[[additional-scenario]]
== Additional Scenarios
[[restoring-bootloader-using-live-disk]]
=== Restoring the bootloader using the Live disk.
Sometimes, especially after a secondary operating systems has been installed, the master boot record gets damaged which then prevents the original Linux system from booting.
If this happens, it is necessary to reinstall *GRUB2* to recreate the original settings. The process not only discovers all installed operating systems, but usually adds them to the *GRUB2* configuration files, so they will all become bootable by *GRUB2*.
.Before you start
. Get the Fedora Live ISO from link:https://download.fedoraproject.org/pub/fedora/linux/releases/27/Workstation/x86_64/iso/Fedora-Workstation-Live-x86_64-27-1.6.iso[getfedora.org].
. Prepare a bootable device using the downloaded ISO, either a CD or a USB.
.Procedure
. Boot the Fedora live system from the bootable device you have created.
. Open the terminal.
. Examine the partition layout and identify the `boot` and the `root` partition.
+
----
$ sudo fdisk -l
----
+
If you are using the default Fedora layout, there will be one `/dev/sda1` partition that holds the `/boot` directory and one `/dev/mapper/fedora-root` that holds the root file system.
. Create the mount point for the root partition.
+
----
$ sudo mkdir -p /mnt/root
----
. Mount the root partition on the mount point.
+
----
$ sudo mount /dev/mapper/fedora-root /mnt/root
----
. Mount the boot partition in the `boot` directory of the filesystem that you have mounted in the previous step.
+
----
$ sudo mount /dev/sda1 /mnt/root/boot/
----
. Mount system processes and devices into the root filesystem in `/mnt/root`.
+
----
$ sudo mount -o bind /dev /mnt/root/dev
$ sudo mount -o bind /proc /mnt/root/proc
$ sudo mount -o bind /sys /mnt/root/sys
$ sudo mount -o bind /run /mnt/root/run
----
. Change your filesystem into the one mounted under `/mnt/root`.
+
----
$ sudo chroot /mnt/root
----
. Reinstall *GRUB2* into the MBR of the primary hard disk.
+
----
$ sudo grub2-install --no-floppy --recheck /dev/sda
----
. Recreate the *GRUB2* configuration files.
+
----
$ sudo grub2-mkconfig -o /boot/grub2/grub.cfg
----
. Exit this temporary root filesystem.
+
----
$ exit
----
. Your bootloader should be now restored. Reboot your computer to boot into your normal system.
+
----
$ sudo systemctl reboot
----
[[using-the-grub-2-boot-prompt]]
==== Using the GRUB2 boot prompt
If improperly configured, *GRUB2* may fail to load and subsequently drop
to a boot prompt. To address this issue, proceed as follows:
\0. Load the XFS and LVM modules
....
. Load the XFS and LVM modules
+
----
insmod xfs
insmod lvm
....
----
\1. List the drives which GRUB 2 sees:
....
. List the drives which *GRUB2* sees:
+
----
grub2> ls
....
----
\2. The output for a dos partition table /dev/sda with three partitons
. Study the output for the partition table of the `/dev/sda` device. It may look similar to the following example on a dos partition table with three partitons.
will look something like this:
....
+
----
(hd0) (hd0,msdos3) (hd0,msdos2) (hd0,msdos1)
....
\3. While the output for a gpt partition table /dev/sda with four
partitions will look something like this:
....
----
+
or similar to this output on a gpt partition table of the `/dev/sda` device with four
partitions.
+
----
(hd0) (hd0,gpt4) (hd0,gpt3) (hd0,gpt2) (hd0,gpt1)
....
----
\4. With this information you can now probe each partition of the drive
and locate your vmlinuz and initramfs files:
....
. Probe each partition of the drive and locate your `vmlinuz` and `initramfs` files.
+
----
ls (hd0,1)/
....
----
+
The outcome of the previous command will list the files on `/dev/sda1`. If this partition contains the `/boot` directory, it will show the full name of `vmlinuz` and `initramfs`.
Will list the files on /dev/sda1. If this partition contains /boot, the
output will show the full name of vmlinuz and initramfs.
\5. Armed with the location and full name of vmlinuz and initramfs you
can now boot your system.
5a. Declare your root partition:
....
. Set the root partition.
+
----
grub> set root=(hd0,3)
....
----
5b. Declare the kernel you wish to use:
....
. Set the desired kernel.
+
----
grub> linux (hd0,1)/vmlinuz-3.0.0-1.fc16.i686 root=/dev/sda3 rhgb quiet selinux=0
# NOTE : add other kernel args if you have need of them
# NOTE : change the numbers to match your system
....
----
5c. Declare the initrd to use:
....
. Set the desired `initrd`.
+
----
grub> initrd (hd0,1)/initramfs-3.0.0-1.fc16.i686.img
# NOTE : change the numbers to match your system
....
----
5d. Instruct GRUB 2 to boot the chosen files:
....
. Boot with the selected settings.
+
----
grub> boot
....
----
\6. After boot, open a terminal.
. When the system starts, open a terminal.
\7. Issue the grub2-mkconfig command to re-create the grub.cfg file
grub2 needed to boot your system:
....
. Enter the `grub2-mkconfig` command to re-create the `grub.cfg` file to enable *GRUB2* to boot your system.
+
----
grub2-mkconfig -o /boot/grub2/grub.cfg
....
----
\8. Issue the grub2-install command to install grub2 to your hard drive
and make use of your config:
....
. Enter the `grub2-install` command to install *GRUB2* to your hard disk to use of your config file.
+
----
grub2-install --boot-directory=/boot /dev/sda
# Note: your drive may have another device name. Check for it with mount command output.
....
[[additional-scenario]]
Additional Scenario
~~~~~~~~~~~~~~~~~~~
----
[[booting-with-configfile-on-different-partition]]
=== Booting the system using a configuration file on a different partition.
It's also possible to boot into a _configfile_ that's located on another
partition. If the user is faced with such a scenario, as is often the
case with multi-boot systems containing Ubuntu and Fedora, the following
steps in the grub rescue shell might become useful to know:
steps in the *GRUB2* rescue shell might become useful to know:
....
.Procedure
. Load necessary modules to read the partitions.
+
----
insmod part_msdos
insmod xfs
insmod lvm
----
. Set the root partition.
+
----
set root='hd0,msdos1'
----
. Set the path to the configuration file.
+
----
configfile /grub2/grub.cfg
....
----
Where, *hd0,msdos1* is the pertinent _boot_ partition, which holds the
grub.cfg file.
.More information
The *hd0,msdos1* line shows the pertinent _boot_ partition, which holds the
`grub.cfg` file.
[[other-grub-2-issues]]
Other GRUB 2 issues
~~~~~~~~~~~~~~~~~~~
[[absent-floppy-disk]]
=== Dealing with the "Absent Floppy Disk" Error
''' Absent Floppy Disk ''': It has been reported by some users that GRUB
2 may fail to install on a partition's boot sector if the computer
floppy controller is activated in BIOS without an actual floppy disk
drive being present. A possible workaround is to run (post OS install)
from rescue mode:
It has been reported by some users that *GRUB2* may fail to install on a partition's boot sector if the computer's floppy controller is activated in BIOS without an actual floppy disk
drive being present. Such situations resulted in an _Absent Floppy Disk_ error.
....
To workaround this issue, go into the rescue mode and install *GRUB2* with the `--no-floppy` option:
----
grub2-install <target device> --no-floppy
....
----
[[setting-a-password-for-interactive-edit-mode]]
Setting a password for interactive edit mode
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
=== Setting a password for interactive edit mode
If you wish to password-protect GRUB2's interactive edit mode *but* you
do not want to require users to enter a password to do a plain, simple,
ordinary boot, create /etc/grub.d/01_users with the following lines:
If you wish to password-protect the *GRUB2* interactive edit mode
without forcing users to enter a password to boot the computer, use this procedure.
....
.Procedure
. Create the `/etc/grub.d/01_users` file.
+
----
cat << EOF
set superusers="root"
export superusers
password root secret
EOF
....
----
To apply your changes run:
....
. Apply your changes.
+
----
grub2-mkconfig -o /boot/grub2/grub.cfg
....
----
You can encrypt the password by using pbkdf2. Use grub2-mkpasswd-pbkdf2
.More information
You can encrypt the password by using *pbkdf2*. Use `grub2-mkpasswd-pbkdf2`
to encrypt the password, then replace the password line with:
....
----
password_pbkdf2 root grub.pbkdf2.sha512.10000.1B4BD9B60DE889A4C50AA9458C4044CBE129C9607B6231783F7E4E7191D8254C0732F4255178E2677BBE27D03186E44815EEFBAD82737D81C87F5D24313DDDE7.E9AEB53A46A16F30735E2558100D8340049A719474AEEE7E3F44C9C5201E2CA82221DCF2A12C39112A701292BF4AA071EB13E5EC8C8C84CC4B1A83304EA10F74
....
----
More details can be found at
https://help.ubuntu.com/community/Grub2/Passwords[Ubuntu Help: GRUB2
Passwords].
Starting from atleast Fedora 21, the `--md5pass` kickstart option must
be set using output from grub2-mkpasswd-pbkdf2.
[NOTE]
====
Starting from Fedora 21, the `--md5pass` kickstart option must
be set using output from the `grub2-mkpasswd-pbkdf2` command.
====
[[using-old-graphics-modes-in-bootloader]]
Using old graphics modes in bootloader
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
=== Using old graphics modes in bootloader
Terminal device is chosen with GRUB_TERMINAL; additional quote from
http://www.gnu.org/software/grub/manual/grub.html#Simple-configuration
Valid terminal output names depend on the platform, but may include
‘console’ (PC BIOS and EFI consoles), ‘serial’ (serial terminal),
‘gfxterm’ (graphics-mode output), ‘ofconsole’ (Open Firmware console),
or ‘vga_text’ (VGA text output, mainly useful with Coreboot).
Valid terminal output names depend on the platform, but may include
`console` (PC BIOS and EFI consoles), `serial` (serial terminal),
`gfxterm` (graphics-mode output), `ofconsole` (Open Firmware console),
or `vga_text` (VGA text output, mainly useful with Coreboot).
The default is to use the platform's native terminal output.
The default in Fedora is gfxterm and to get the legacy graphics modes
you need to set GRUB_TERMINAL to right variable from the description
above in /etc/default/grub
The default in Fedora is `gfxterm` and to get the legacy graphics modes
you need to set GRUB_TERMINAL to the right variable from the description
above in `/etc/default/grub`.
[[enable-serial-console-in-grub]]
Enable Serial Console in Grub
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[[enabling-serial-console-in-grub]]
=== Enabling Serial Console in GRUB2
To enable Serial console in grub add the following entry's to
/etc/default/grub
To enable Serial console in grub:
( Adjust baudrate/parity/bits/flow control to fit your environment and
cables)
....
. Add the following entry to `/etc/default/grub`. Adjust `baudrate`, `parity`, `bits`, and `flow` controls to fit your environment and cables.
+
----
GRUB_CMDLINE_LINUX='console=tty0 console=ttyS0,115200n8'
GRUB_TERMINAL=serial
GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"
....
And re-generate grub
----
. Re-generate the GRUB2 config file.
+
`grub2-mkconfig -o /boot/grub2/grub.cfg`
[[further-reading]]
Further Reading
---------------
== Further Reading
* http://www.gnu.org/software/grub/manual/grub.html
* Features/Grub2