Help

#ifdef MAIN Welcome to the boot loader of UHU-Linux 1.2 ☺ #else #ifdef INSTALLER Welcome to the installer of UHU-Linux 1.2 ☺ #else Welcome to the installer floppy disk of UHU-Linux 1.2 ☺ #endif #endif

Help is available in the following topics:

· Using the help (you can also press F1 again to get there)

· Using the boot loader, available keys

· Description of the options

· The most important boot parameters to control the Linux system

Using the Help

To navigate in the help use the following keys:

Up: scroll upwards, select previous link
Down: scroll downwards, select next link
Left, Backspace: back to the previous help page
Right, Enter, Space: follow link
Page Up: scroll one page upwards
Page Down: scroll one page downwards
Home: jump to the top of the page
End: jump to the bottom of the page
Esc: leave the help

The help is context sensitive, which means that the opening page depends on the item last used and on the boot parameter being edited. By following the links, however, it's always possible to reach any help page.

⇦ Back to the main menu.

Keys

Use Up and Down arrows, Page Up and Page Down to select the system to be booted.

Use the letters, digits, symbols, space, left and right arrows, Home and End, Backspace and Delete to edit the boot parameters.

Press Enter to boot the selected entry.

F1 brings up the Help.

With F2 ACPI can be turned off.

Using F3 debug mode can be activated. #ifndef MAIN

F4 lets you set the installer's video mode. #endif

F9 lets you choose between English and Hungarian language and keyboard layout.

With F10 you can power off the computer. It doesn't work on some machines.

F12 toggles the clock. Note that the value of the CMOS clock is displayed, which may or may not be in the time zone you expect.

Alt+SysRq+O is a hotkey combo for power off, while Alt+SysRq+B immediately reboots the system. ⚠ Warning! Do not use these under VMware, except if you exactly know what you're doing!

Esc switches to the text interface of the GRUB boot loader. Here you can not only launch the existing entries but also boot an arbitrary file.

⇦ Back to the main menu.

Text Mode of GRUB

Pressing Esc leaves the graphical screen and takes you to the text interface of GRUB. #ifdef BOOTFLOPPY The GRUB with network support only contains the text interface. #endif

Text mode GRUB has a much more old-fashioned look. It is a little bit harder to use it, but in the mean time, it is more powerful than the graphical one, since here not only the already existing entries can be booted, but other ones can be set up too.

The text mode only speaks English and supports only American keyboard layout.

The following topics exist about details on GRUB's text mode:

· Using the Text Mode

· Keywords of GRUB

· Partition and File Names

· Tab Completion

Further documentation is available within the grub package as an info page.

⇦ Back to the Keys.

Text Mode of GRUB: Keys



In the text menu system press e to display the details of the selected option. You get one or more rows. Example:

kernel (hd0,0)/boot/bzImage
initrd (hd0,0)/boot/initrd

To alter a line, select it and perss e again. Press Enter to confirm the changes you made or Esc to cancel them. Once you're done with it, you can edit other lines as well. Press d to delete a line, o and O to insert a new line after or before the current one. E.g. the lines above can easily be altered to this:

kernel (hd1,2)/boot/bzImage
initrd (hd1,2)/boot/initrd

Finally the command list can be booted by pressing b.

In the menu pressing c takes you to command line mode. Here you can type help to get help about the commands. Esc brings you back to the menu.

⇦ Back to the Text Mode of GRUB.

Text Mode of GRUB: Keywords

The kernel keyword is used to give the kernel, e.g.:
kernel (hd0,4)/boot/bzImage

Kernel options may be given too, e.g.:
kernel (hd0,4)/boot/bzImage debug acpi=off vga=4

To specify an initial ramdisk, use the initrd command:
initrd (hd0,4)/boot/initrd

A different boot loader can be loaded by the chainloader command, e.g.:
chainloader (hd0,0)+1

To launch the specified system, type boot in command line mode, or press b in the menu.

For further details type help in command line mode.

⇦ Back to the Text Mode of GRUB.

Text Mode of GRUB: File Names

To name a disk or a partition use following expressions using parentheses:

(fd0) – first floppy disk
(fd1) – second floppy disk

(cd) – CD (in case GRUB was booted from CD)

(hd0) – first hard disk
(hd0,0) – first primary partition of first hard disk
(hd0,1) – second primary partition of first hard disk
(hd0,2) – third primary partition of first hard disk
(hd0,3) – fourth primary partition of first hard disk
(hd0,4) – first logical partition of first hard disk
(hd0,5) – second logical partition of first hard disk
...

(hd1) – second hard disk
(hd1,0) – first partition of second hard disk
...

(hd2) – third hard disk
...
...

(nd) – TFTP server (only in network aware GRUB)

Reading from CD is only supported if the BIOS booted this GRUB from CD.

The device identifier should be followed by the file to be loaded. Here are two basic possibilites:

· Use file name, e.g. /boot/bzImage. GRUB is able to read FAT, Minix, Ext2, Ext3, ReiserFS, JFS, XFS, UFS2 and iso9660 file systems, but not NTFS. Use absolute path, and use / as path separator regardless of the file system, \ is incorrect.

· List of blocks, e.g. +1 means the first block of the partition or drive.

⇦ Back to the Text Mode of GRUB.

Text Mode of GRUB: Tab Completion

When typing an option in GRUB's text mode (both after pressing e on a particular row to edit, and in command line mode) Tab helps us to complete the line.

Example:

Hitting Tab on an empty line lists the available keywords. Type

ker

and press Tab again. This completes the word to kernel. Type the opening parenthesis:

kernel (

Tab again shows the available drives. Type hd0:

kernel (hd0

and Tab again. This time the partitions are listed along with their file systems' type. Type the partition, the closing parenthesis and a slash:

kernel (hd0,4)/

Here Tab completes on file names so it's easy to find the required file. E.g. if we have typed:

kernel (hd0,4)/boot/bz

then most likely Tab will complete to this:

kernel (hd0,4)/boot/bzImage

⇦ Back to the Text Mode of GRUB.

Language and Keyboard Layout

F9 lets you choose between English and Hungarian language and keyboard layout.

⇦ Back to Keys.

Available Boot Options

#ifdef MAIN By selecting one of the offered boot options you can boot the corresponding operating system installed to your computer. To control which options appear, edit /boot/grub/menu.lst in your running UHU-Linux system. #endif #ifdef BOOTFLOPPY

· Installation from the First Partition

· GRUB with Network Support

· Smart Boot Manager

· FreeDOS #endif #ifdef INSTALLER

· Installation

· Rescue System #endif

· Memory Test

⇦ Back to Main Menu. #ifdef BOOTFLOPPY

Installation from the First Partition

This option launches the installer of UHU-Linux in case the two necessary files (boot/bzImage and boot/initrd on the CD) were previously copied to the boot directory of the first partition of the first hard disk. On typical DOS and Windows installations this means they were copied to C:\boot\bzImage and C:\boot\initrd.

The partition has to contain FAT or some Linux file system, as GRUB is unable to read NTFS.

If you copied these two files to another partition, then press Esc to enter the text interface of GRUB where an alternate path can be specified as well.

⇦ Back to the Available Boot Options.

GRUB with Network Support

For technical reasons two different version of GRUB are present on the boot floppy.

The currently running GRUB doesn't contain network support, however, due to its lower memory needs it is able to display graphical screen.

Network aware GRUB has support for about thirty different kind of network cards, is able to perform DHCP requests to get the host's settings, and load files from a TFTP server. However it needs more memory, and unfortunately this along with the graphical support doesn't fit in PC's base memory, hence we only have the text interface.

The first option of the network aware GRUB, Boot from Network first requests an IP address via DHCP, then fetches /tftpboot/bzImage and /tftpboot/initrd using TFTP. It's possible to edit the options, so different filenames can be given too.

⇦ Back to the Available Boot Options.

Smart Boot Manager

The Smart Boot Manager option loads the boot manager with the same name. Smart Boot Manager offers you to choose from all the hard disk partitions, floppy and CD drives.

If you like this boot loader, install the UHU package sbm and use the command sbminst to install this into your hard drive, replacing GRUB.

For further information, visit http://btmgr.sourceforge.net/.

⇦ Back to the Available Boot Options.

FreeDOS

Using FreeDOS takes you to a minimal FreeDOS system.

Here fdisk lets you partition your hard drive, while format can create a file system.

Using basic DOS file commands you can copy the boot/bzImage and boot/initrd files from your CD (usually it's called D:, but a different letter is also possible) to the FAT file system in your hard disk.

⇦ Back to the Available Boot Options. #endif #ifdef INSTALLER

Installation

Choose Installation to begin installing your UHU-Linux from CD.

⇦ Back to the Available Boot Options.

Rescue System

Rescue System takes you to a basic Linux system where you can repair your main Linux system or perform some other minor operations.

Alt plus function keys switch among different text consoles.

⇦ Back to the Available Boot Options. #endif

Memory Test

Memtest86+ checks the computer's memory.

Unfortunately there are quite a lot of computers around that have faulty memory modules. Such a computer is, of course, unable to operate correctly.

This program runs and tests your memory again and again until it is stopped. In case of faulty hardware usually at least one error occurs within an hour, which is printed on the big blue part of the screen that is emtpy at the beginning. However, the longer you leave this program running (for several days if possible) the more sure you can be that the memory modules are correct.

If an error is displayed, it is still not sure that the memory moduls are bad, it's possible that the motherboard, processor or other component of the system is faulty. In most of the cases, however, it is the memory that misbehaves.

In case memory test shows errors (maybe only one error during some days) it's important to replace the faulty component of the system as soon as possible. Using a computer that is not able to correctly execute the commands of the operating system can easily lead to serious data loss or full corrpution of your file system.

Having the machine overclocked can also be a reason of failure. Reset these values to their original factory value and repeat the test. If the errors occur again then the faulty component (most likely a memory module) has to be replace. #ifdef INSTALLER

This menu item will be available from within the boot loader of the installed system, unless you choose not to install the memtest86+ package. #endif

For further information visit http://www.memtest.org/.

⇦ Back to the Available Boot Options.

Boot Parameters

Description is available on the following boot parameters:

· acpi – power management
· debug – debug mode #ifndef MAIN
· layout – graphical resolution of the installer
· LANG – the language of the installer #endif
· ide – the way IDE disks are accessed #ifndef INSTALLER
· 3, 5 – text/graphical mode #endif

The most common parameters can be set by the function keys, the less common ones have to be typed manually.

There are plenty other options as well, it would be impossible to list them all. These are mainly parameters to the Linux kernel, but #ifndef MAIN e.g. debug is an option of both the kernel and the installer, while layout and LANG are only used by the installer. #else sometimes influence the behavior of a system utility. #endif

These parameters only have any affect if Linux is booted.

⇦ Back to the Main Menu. #ifndef MAIN

Boot Parameters: layout

If the installer cannot find a suitable graphical mode, try setting vesa first. If this doesn't work either, choose vga. The corresponding parameters are:

layout=vesa – VESA mode
layout=vga – VGA mode

The values can also be selected with F4.

⇦ Back to the Boot Parameters.

Boot Parameters: LANG

LANG sets the language of the installer. Possible values are:

LANG=en_US – the installer runs in English
LANG=hu_HU – the installer runs in Hungarian

The default is the value that GRUB uses, which can be set with F9.

⇦ Back to the Boot Parameters. #endif

Boot Parameters: debug

In case the debug option is given, UHU-Linux kernel prints debug message to the #ifdef MAIN screen. #else screen and the installer also runs in debug mode.

Having finished the installation, press Alt+F5, Alt+F6, Alt+F7 and Alt+F8 to switch to the virtual console No 5-8, and exit from the shell in each of them (e.g. by pressing Ctrl+D). #endif

This parameter can also be turned on with F3.

⇦ Back to the Boot Parameters.

Boot Parameters: acpi

The old way of accessing power management features of computers is to use APM (Advanced Power Management). The newer technology is called ACPI (Advanced Configuration and Power Interface). ACPI is actually much more than just power management, some new computers cannot even be booted without ACPI support, or it leads to IRQ problems. Unfortunately sometimes it is ACPI itself that causes problems (IRQ conflict, freeze), usually due to faulty BIOS implementations. (A BIOS upgrade often helps.)

There are three basic choices:

· use ACPI (needs BIOS support)
· use APM (needs BIOS support)
· none of them

The recommended and the default is ACPI.

Options to control ACPI:

· acpi=on – turns on ACPI support (default of UHU-Linux)
· acpi=force – turns on ACPI even if BIOS seems buggy
· acpi=ht – only use ACPI for HyperThreading
· acpi=off – turns off ACPI

Some values can be selected by pressing F2.

If the computer doesn't support ACPI or it is turned off then APM automatically takes its place, in case BIOS supports that one. To disable APM use the option noapm.

⇦ Back to the Boot Parameters.

Boot Parameters: ide

If problems arise with IDE disks, try disabling DMA mode with this option:

ide=nodma

⇦ Back to the Boot Parameters. #ifndef INSTALLER

Boot Parameters: runlevels

Use on digit to give the runlevel.

3 – runlevel 3: text mode
5 – runlevel 5: graphical mode

The default is stored in the booted Linux system, in /etc/inittab.

⇦ Back to the Boot Parameters. #endif