Applies to SUSE Linux Enterprise Micro 5.3

11 Boot parameters #

SUSE Linux Enterprise Micro allows setting several parameters during boot, for example choosing the source of the installation data or setting the network configuration.

Using the appropriate set of boot parameters helps simplify your installation procedure. Many parameters can also be configured later using the linuxrc routines, but using the boot parameters is easier. In some automated setups, the boot parameters can be provided with initrd or an info file.

The way the system is started for the installation depends on the architecture—system start-up is different for PC (AMD64/Intel 64) or mainframe, for example. If you install SUSE Linux Enterprise Micro as a VM Guest on a KVM or Xen hypervisor, follow the instructions for the AMD64/Intel 64 architecture.

Note: Boot options and boot parameters

The terms Boot Parameters and Boot Options are often used interchangeably. In this documentation, we mostly use the term Boot Parameters.

11.1 Using the default boot parameters #

Generally, selecting Installation starts the installation boot process.

If problems occur, use Installation—ACPI Disabled or Installation—Safe Settings. For more information about troubleshooting the installation process, refer to Chapter 14, Troubleshooting.

The menu bar at the bottom of the screen offers some advanced functionality needed in some setups. Using the function keys (F1 ... F12), you can specify additional options to pass to the installation routines without having to know the detailed syntax of these parameters (see Chapter 11, Boot parameters). A detailed description of the available function keys is available in Section 11.2.1, “The boot screen on machines equipped with traditional BIOS”.

11.2 PC (AMD64/Intel 64/AArch64) #

This section describes changing the boot parameters for AMD64, Intel 64, and AArch64.

11.2.1 The boot screen on machines equipped with traditional BIOS #

The boot screen displays several options for the installation procedure. Boot from Hard Disk boots the installed system and is selected by default, because the CD is often left in the drive. Select one of the other options with the arrow keys and press Enter to boot it. The relevant options are:

Installation: The normal installation mode. All modern hardware functions are enabled. In case the installation fails, see F5Kernel for boot parameters that disable potentially problematic functions.
More › Boot Linux System: Boot a Linux system that is already installed. You will be asked from which partition to boot the system.
More › Check Installation Media: This option is only available when you install from media created from downloaded ISOs. In this case it is recommended to check the integrity of the installation medium. This option starts the installation system before automatically checking the media. In case the check was successful, the normal installation routine starts. If a corrupt media is detected, the installation routine aborts. Replace the broken medium and restart the installation process.
More › Memory Test: Tests your system RAM using repeated read and write cycles. Terminate the test by rebooting. For more information, see Section 14.4, “Boot failure”.

Figure 11.1: The boot screen on machines with a traditional BIOS #

Use the function keys shown at the bottom of the screen to change the language, screen resolution, installation source or to add an additional driver from your hardware vendor:

F1Help

Get context-sensitive help for the active element of the boot screen. Use the arrow keys to navigate, Enter to follow a link, and Esc to leave the help screen.

F2Language

Select the display language and a corresponding keyboard layout for the installation. The default language is English (US).

F3Video Mode

Select various graphical display modes for the installation. By Default the video resolution is automatically determined using KMS (“Kernel Mode Setting”). If this setting does not work on your system, choose No KMS and, optionally, specify vga=ask on the boot command line to get prompted for the video resolution. Choose Text Mode if the graphical installation causes problems.

F4Source

Normally, the installation is performed from the inserted installation medium. Here, select other sources, like FTP or NFS servers, or configure a proxy server.

F5Kernel

If you encounter problems with the regular installation, this menu offers to disable a few potentially problematic functions. If your hardware does not support ACPI (advanced configuration and power interface) select No ACPI to install without ACPI support. No local APIC disables support for APIC (Advanced Programmable Interrupt Controllers) which may cause problems with some hardware. Safe Settings boots the system with the DMA mode (for CD/DVD-ROM drives) and power management functions disabled.

If you are not sure, try the following options first: Installation—ACPI Disabled or Installation—Safe Settings. Experts can also use the command line (Boot Options) to enter or change kernel parameters.

F6Driver

Press this key to notify the system that you have an optional driver update for SUSE Linux Enterprise Micro. With File or URL, load drivers directly before the installation starts. If you select Yes, you are prompted to insert the update disk at the appropriate point in the installation process.

11.2.2 The boot screen on machines equipped with UEFI #

UEFI (Unified Extensible Firmware Interface) is a new industry standard which replaces and extends the traditional BIOS. The latest UEFI implementations contain the “Secure Boot” extension, which prevents booting malicious code by only allowing signed boot loaders to be executed.

The boot manager GRUB 2, used to boot machines with a traditional BIOS, does not support UEFI, therefore GRUB 2 is replaced with GRUB 2 for EFI. If Secure Boot is enabled, YaST will automatically select GRUB 2 for EFI for installation. From an administrative and user perspective, both boot manager implementations behave the same and are called GRUB 2 in the following.

Tip: Using additional drivers with Secure Boot

When installing with Secure Boot enabled, you cannot load drivers that are not shipped with SUSE Linux Enterprise Micro. This is also true of drivers shipped via SolidDriver, because their signing key is not trusted by default.

To load drivers not shipped with SUSE Linux Enterprise Micro, do either of the following:

Before the installation, add the needed keys to the firmware database via firmware/system management tools.
Use a bootable ISO that will enroll the needed keys in the MOK list on the first boot.

The boot screen displays several options for the installation procedure. Change the selected option with the arrow keys and press Enter to boot it. The relevant options are:

Installation: The normal installation mode. All modern hardware functions are enabled. In case the installation fails, see F5Kernel for boot parameters that disable potentially problematic functions.
More › Rescue System: Starts a minimal Linux system without a graphical user interface. For more information, see
More › Boot Linux System: Boot a Linux system that is already installed. You will be asked from which partition to boot the system.
More › Check Installation Media: This option is only available when you install from media created from downloaded ISOs. In this case it is recommended to check the integrity of the installation medium. This option starts the installation system before automatically checking the media. In case the check was successful, the normal installation routine starts. If a corrupt media is detected, the installation routine aborts.

The Boot Screen on Machines with UEFI

Figure 11.2: The boot screen on machines with UEFI #

GRUB 2 for EFI on SUSE Linux Enterprise Micro does not support a boot prompt or function keys for adding boot parameters. By default, the installation will be started with American English and the boot media as the installation source. A DHCP lookup will be performed to configure the network. To change these defaults or to add boot parameters you need to edit the respective boot entry. Highlight it using the arrow keys and press E. See the on-screen help for editing hints (note that only an English keyboard is available now). The Installation entry will look similar to the following:

setparams 'Installation'

   set gfxpayload=keep
   echo 'Loading kernel ...'
   linuxefi /boot/x86_64/loader/linux splash=silent
   echo 'Loading initial ramdisk ...'
   initrdefi /boot/x86_64/loader/initrd

Add space-separated parameters to the end of the line starting with linuxefi. To boot the edited entry, press F10. If you access the machine via serial console, press Esc–0. A complete list of parameters is available at https://en.opensuse.org/Linuxrc.

11.3 List of important boot parameters #

This section contains a selection of important boot parameters.

11.3.1 General boot parameters #

autoyast=URL

The autoyast parameter specifies the location of the autoinst.xml control file for automatic installation.

manual=<0|1>

The manual parameter controls whether the other parameters are only default values that still must be acknowledged by the user. Set this parameter to 0 if all values should be accepted and no questions asked. Setting autoyast implies setting manual to 0.

Info=URL

Specifies a location for a file from which to read additional options.

upgrade=<0|1>

To upgrade SUSE Linux Enterprise Micro, specify Upgrade=1.

dud=URL

Load driver updates from URL.

Set dud=ftp://ftp.example.com/PATH_TO_DRIVER or dud=http://www.example.com/PATH_TO_DRIVER to load drivers from a URL. When dud=1 you will be asked for the URL during boot.

language=LANGUAGE

Set the installation language. Some supported values are cs_CZ, de_DE, es_ES, fr_FR, ja_JP, pt_BR, pt_PT, ru_RU, zh_CN, and zh_TW.

acpi=off

Disable ACPI support.

noapic

No logical APIC.

nomodeset

Disable KMS.

textmode=1

Start installer in text mode.

console=SERIAL_DEVICE[,MODE]

SERIAL_DEVICE can be an actual serial or parallel device (for example ttyS0) or a virtual terminal (for example tty1). MODE is the baud rate, parity and stop bit (for example 9600n8). The default for this setting is set by the mainboard firmware. If you do not see output on your monitor, try setting console=tty1. It is possible to define multiple devices.

11.3.2 Configuring the network interface #

Important: Configuring the network interface

The settings discussed in this section apply only to the network interface used during installation.

The network will only be configured if it is required during the installation. To force the network to be configured, use the netsetup or ifcfg parameters.

netsetup=VALUE

netsetup=dhcp forces a configuration via DHCP. Set netsetup=-dhcp when configuring the network with the boot parameters hostip, gateway and nameserver. With the option netsetup=hostip,netmask,gateway,nameserver the installer asks for the network settings during boot.

ifcfg=INTERFACE[.VLAN]=[.try,]SETTINGS

INTERFACE can be * to match all interfaces or, for example, eth* to match all interfaces that start with eth. It is also possible to use MAC addresses as values.

Optionally, a VLAN can be set behind the interface name, separated by a period.

If SETTINGS is dhcp, all matching interfaces will be configured with DHCP. If you add the try option, configuration will stop when the installation repository can be reached via one of the configured interfaces.

Alternatively you use static configuration. With static parameters, only the first matching interface will be configured, unless you add the try option. This will configure all interfaces until the repository can be reached.

The syntax for the static configuration is:

ifcfg=*="IPS_NETMASK,GATEWAYS,NAMESERVERS,DOMAINS"

Each comma separated value can in turn contain a list of space character separated values. IPS_NETMASK is in the CIDR notation, for example 10.0.0.1/24. The quotes are only needed when using space character separated lists. Example with two name servers:

ifcfg=*="10.0.0.10/24,10.0.0.1,10.0.0.1 10.0.0.2,example.com"

Tip: Other networking parameters

The ifcfg boot parameter is very powerful and allows you to set almost all networking parameters. In addition to the parameters mentioned above, you can set values for all configuration options (comma separated) from /etc/sysconfig/network/ifcfg.template and /etc/sysconfig/network/config. The following example sets a custom MTU size on an interface otherwise configured via DHCP:

ifcfg=eth0=dhcp,MTU=1500

hostname=host.example.com

Enter the fully qualified host name.

domain=example.com

Domain search path for DNS. Allows you to use short host names instead of fully qualified ones.

hostip=192.168.1.2[/24]

Enter the IP address of the interface to configure. The IP can contain the subnet mask, for example hostip=192.168.1.2/24. This setting is only evaluated if the network is required during the installation.

gateway=192.168.1.3

Specify the gateway to use. This setting is only evaluated if the network is required during the installation.

nameserver=192.168.1.4

Specify the DNS server in charge. This setting is only evaluated if the network is required during the installation.

domain=example.com

Domain search path. This setting is only evaluated if the network is required during the installation.

11.3.3 Specifying the installation source #

If you are not using DVD or USB flash drive for installation, specify an alternative installation source.

install=SOURCE

Specify the location of the installation source to use. Possible protocols are cd, hd, slp, nfs, smb (Samba/CIFS), ftp, tftp, http, and https. The default option is cd.

To install over an encrypted connection, use an https URL. If the certificate cannot be verified, disable certificate checking with the sslcerts=0 boot parameter.

If an http, https, ftp, tftp, or smb URL is given, you can authenticate by specifying the user name and password with the URL. Example:

install=https://USER:PASSWORD@SERVER/DIRECTORY/DVD1/

In case of a Samba or CIFS installation, you can also specify the domain that should be used:

install=smb://WORKDOMAIN;USER:PASSWORD@SERVER/DIRECTORY/DVD1/

To use cd, hd or slp, set them as the following example:

install=cd:/
install=hd:/?device=sda/PATH_TO_ISO
install=slp:/

11.3.4 Specifying remote access #

Only one of the different remote control methods should be specified at a time. The different methods are: SSH, VNC, remote X server. For information about how to use the parameters listed in this section, see Chapter 13, Remote installation.

display_ip=IP_ADDRESS: Display_IP causes the installing system to try to connect to an X server at the given address.
Important: X authentication mechanism
The direct installation with the X Window System relies on a primitive authentication mechanism based on host names. This mechanism is disabled on current SUSE Linux Enterprise Micro versions. Installation with SSH or VNC is preferred.
vnc=1: Enables a VNC server during the installation.
vncpassword=PASSWORD: Sets the password for the VNC server.
ssh=1: ssh enables SSH installation.
ssh.password=PASSWORD: Specifies an SSH password for the root user during installation.

11.4 Advanced setups #

To configure access to a local RMT or supportconfig server for the installation, you can specify boot parameters to set up these services during installation. The same applies if you need IPv6 support during the installation.

11.4.1 Using IPv6 for the installation #

By default you can only assign IPv4 network addresses to your machine. To enable IPv6 during installation, enter one of the following parameters at the boot prompt:

Accept IPv4 and IPv6

ipv6=1

Accept IPv6 only

ipv6only=1

11.4.2 Using a proxy for the installation #

In networks enforcing the usage of a proxy server for accessing remote web sites, registration during installation is only possible when configuring a proxy server.

On systems with traditional BIOS, press F4 on the boot screen and set the required parameters in the HTTP Proxy dialog.

On Systems with UEFI BIOS, provide the boot parameter proxy at the boot prompt:

On the boot screen, press E to edit the boot menu.
Append the proxy parameter to the linux line in the following format:
```
proxy=https://proxy.example.com:PORT
```
If the proxy server requires authentication, add the credentials as follows:
```
proxy=https://USER:PASSWORD@proxy.example.com:PORT
```
If the proxy server's SSL certificate cannot be verified, disable certificate checking with the sslcerts=0 boot parameter.
The outcome will be similar to the following:
Figure 11.3: GRUB options editor #
Press F10 to boot with the new proxy setting.

11.4.3 Enabling SELinux support #

Enabling SELinux upon installation start-up enables you to configure it after the installation has been finished without having to reboot. Use the following parameters:

security=selinux selinux=1

11.4.4 Scale user interface for high DPI #

If your screen uses a very high DPI, use the boot parameter QT_AUTO_SCREEN_SCALE_FACTOR. This scales font and user interface elements to the screen DPI.

QT_AUTO_SCREEN_SCALE_FACTOR=1

11.4.5 Using CPU mitigations #

The boot parameter mitigations lets you control mitigation options for side-channel attacks on affected CPUs. Its possible values are:

auto. Enables all mitigations required for your CPU model, but does not protect against cross-CPU thread attacks. This setting may impact performance to some degree, depending on the workload.

nosmt. Provides the full set of available security mitigations. Enables all mitigations required for your CPU model. In addition, it disables Simultaneous Multithreading (SMT) to avoid side-channel attacks across multiple CPU threads. This setting may further impact performance, depending on the workload.

off. Disables all mitigations. Side-channel attacks against your CPU are possible, depending on the CPU model. This setting has no impact on performance.

Each value comes with a set of specific parameters, depending on the CPU architecture, the kernel version, and on the vulnerabilities that need to be mitigated. Refer to the kernel documentation for details.

11.5 More information #

You can find more information about boot parameters in the openSUSE wiki at https://en.opensuse.org/SDB:Linuxrc#Parameter_Reference.