Linux Troubleshooting Bible [Electronic resources] نسخه متنی

Choosing Hardware

By using computer hardware that is both supported and contains the recommended amount of power (RAM, CPU, and so forth), you have the best chance of successfully installing a Red Hat Linux system. This section presents some of the issues related to making sure you have computer hardware that will work for Fedora and Red Hat Linux systems.

Random Access Memory (RAM)

Having enough RAM installed on your computer is critical to a successful installation of Fedora or Red Hat Linux. Recommended memory amounts for Fedora Core are as follows:

Text mode: 64MB (minimum)

Graphical mode: 192MB (mimimum)

Graphical mode: 256MB (recommended)

If you are running in graphical mode with less than 192MB, you will almost certainly be unhappy with performance at some point. To run a Red Hat Linux system on less than 64MB of RAM, you might consider looking into the RULE project (www.rule-project.org ). RULE (Run Up2date Linux Everywhere) is a version of Red Hat Linux that was modified to run on less powerful computers.

If you meet or exceed the minimum RAM requirement, in most cases the Anaconda installer will detect it. So, the installation should just work without any special consideration of RAM. However, there are some cases where the kernel cannot detect the actual amount of RAM. In these cases, you can run a memory test to find out how much RAM you actually have (as explained in the next section), then provide an option when you boot the install process to tell the kernel how much memory to use.

Testing Memory From Installation Boot Prompt

To run a memory test, boot from the first installation CD (Fedora or Red Hat Linux). Then type the following at the boot prompt:

boot:  memtest86

The

memtest86 feature runs the

memtest86 stand-alone memory diagnostic utility. Besides accurately reporting the total amount of available memory, memtest86 also tests for memory failures, level 1 and level2 cache memory, and reserved memory. It also reports on the memory chipset and method used to find memory size (e820 by default). For more information on

memtest86 , refer to www.memtest86.com.

Checking Memory after Installation

After Fedora or Red Hat Linux is installed, you can find out how much memory is being used by checking

/proc/meminfo as follows:

$  cat /proc/meminfo

If you are about to do an upgrade or a fresh install, you can compare the amount shown in the cache size line to the Memory line shown in the

memtest86 output. If not all the memory is being detected, you might consider providing the higher amount of RAM as an option when you boot Fedora or Red Hat Linux installation. (See the Selecting Memory Sizes section later in this chapter.)

Installation Media (CD-ROM)

CD-ROMs are still the most common medium for installing Linux systems. Red Hat Linux 9 and Fedora Core 1 each comes on a set of three CDs that you can get by downloading from the Internet or with books such as Red Hat Linux Bible. If you download the CD ISO images on your own, then burn them on to CDs, here are a few tips to help insure that you make good copies of those media:

Consider purchasing media or getting copies from a friend if you have a dial-up connection. Even a broadband connection will take 1 to 3 hours for each CD to download.

Run the

md5sum command on each ISO image. For example, if you downloaded Fedora Core 1 (code-named yarrow), with the images in the current directory, type

#  md5sum yarrow*iso > myMD5SUM

Compare the contents of myMD5SUM to the MD5SUM you downloaded along with the ISO images (MD5SUM is a small text file contained in the same directory as the ISOs).

The most recent recommendation from Red Hat, Inc., for a command line to burn CD is to use the

cdrecord command in dao mode. Here's that command line showing how to burn the first Fedora Core 1 CD from the current directory (repeat this step for the other two CDs in the installation set):

#  cdrecord -v -dao -eject -pad padsize-150s yarrow-i386-disc1.iso

If you are burning bad copies, slow down the burn process (even as low as 2× or 4×).

Use CD-R instead of CD-RW media.

Video Cards

If your video card or monitor is improperly detected, the screen may be too garbled to be able to complete installation. Here are some suggestions if the install process is not able to properly probe and configure your video hardware:

Run the install in text mode (linux text)-After you boot the computer, you can fix the GUI using redhat-config-xfree86 or the XFree86 tools. As long as you are able to see the screen in text mode, you can continue with the installation. (This issue is addressed in Failing to Start the Install Process section later in this chapter.)

Try setting the

vga= option-If you have a nonstandard size monitor or undetectable video card, you can try to set the

vga= option at the boot prompt when you run the install. Laptop computers are particularly at risk for not being detected properly.

Using the

vga= option at the boot prompt, Anaconda can use the video BIOS to modify the display mode being used. This takes place before the kernel is even booted to start the install process. To display a list of available VGA settings to choose from, you can boot the install process using the following

vga= option:

boot:  linux vga-ask

When you see the first message, press Enter to see a list of VGA settings you can choose from and it will appear as follows:

Press <RETURN> to see video modes available.
SPACE to continue or wait 30 secs
Video adapter: VESA VGA
Mode: COLSxROWS:
0    0F00 80x25
1    0F01 80x50
2    0F02 80x43
3    0F03 80x28
4    0F05 80x30
5    0F06 80x34
6    0F07 80x60
7    0100 40x25
Enter node number or 'scan':

You can type

scan to scan for additional modes or type a mode number (from

0 to

7 in the example above) to choose a particular mode. As an alternative, you can choose a video mode directly with the

vga= option. Table 2-1 contains some examples of

vga options and the values they represent.

The

vga values can also be entered as hexadecimal numbers. Table 2-2 shows the hexadecimal values for different resolutions and numbers of colors (this table is from the Framebuffer HOWTO).

For more information on VGA modes, refer to the

svga.txt file in

/usr/src/linux-2.*/Documentation directory. Refer to Chapter 7 for more in-depth coverage on troubleshooting video cards.

Laptop Problems

Some specific problems known to cause laptop installations to fail in Fedora Core 1 include the following:

Boot fails on LCD displays-Some LCD displays may prevent the installation process from starting. To get around the problem you can try disabling the frame buffer as follows:

boot: linux nofb

Installation not starting on Sony VAIO notebooks-You may need to temporarily disable some PCI devices on Sony VAIO notebooks to get Fedora to install properly. Here are options you can try to add to the boot prompt to get installation to work:

boot:  linux pci-off idel = 0x180, 0x386

If all Else Fails...

Even the sections you just read will help you take you through the type of hardware and media you should have used to install Fedora or Red Hat Linux; it's quite possible that some hardware that is up to specifications will not work. If you have gone through the information in this chapter and are still having failures installing Linux, I suggest you do the following:

Bugzilla-For now, Fedora and other Red Hat Linux distributions all log bug reports into Bugzilla database of Red Hat, Inc.: http://bugzilla.redhat.com . Try searching the Bugzilla database for your computer hardware to see if someone else has had trouble installing on it. If nothing turns up, consider entering a bug report yourself. Then track the bug to see how people on the project respond to the report.

Google-Use www.google.com or your favorite search engine to search for the word Linux, along with the name of your motherboard, chipset, or computer model. Although you may not be able to get Linux to install on your particular PC hardware, chances are someone else has tried and has shared their experiences on a website or mailing list somewhere. Googling might tell you about other peoples' results installing on the hardware you have.

Installation mailing lists-There are mailing lists devoted to answering questions about Fedora and Red Hat Linux. You can access the Red Hat installation list from www.redhat.com/mailman/listinfo/redhat-install-list . For Fedora, try the general.list: www.redhat.com/mailman/listinfo/fedora-list .