Error Messages Explained

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Error Messages Explained
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-''Graham Morrison decodes the secret meaning behind the most common Linux error messages and helps you cure the problems in the process.''+== Distro installation ==
-Some people are scared of Linux+'''Every Linux distribution has a different installation routine, and each creates problems. Ubuntu might work for one machine and not for another. A machine with a working Ubuntu installation may not work with Fedora, or OpenSUSE, or Linux Mint, or Mandriva...'''
-because the error messages it+ 
-produces seem to imply the coming+=== '''ERROR: Can’t boot from CD/DVD''' ===
-of the apocalypse. And there’s a great+ 
-number of them. If you search for the word+If you’re new to Linux, this is often your first experience of the
-‘Error’ in our forums, you get more than 150+operating system: you insert your new disc into the drive and
-pages of results. That’s a lot of people+restart the machine, only to be greeted by the same operating
-experiencing a lot of problems.+system you were using before. The problem is that your hard drive
-The biggest difficulty for these users isn’t the+has a higher boot priority than your optical drive. Many modern
-number of error messages; it’s trying to get+BIOSes include a boot menu from where you can change the
-something useful out of them. What does ‘Kernel+priority of your devices on the fly – try pressing the ‘Escape’ key or
-Oops’ mean, for example, or ‘PCI Can’t Allocate’?+F12 when you first see something on the screen. From there, you
-Linux error messages are obtuse, difficult to+can simply choose to boot from the optical drive.
-understand and rarely helpful. Which is a pity,+ 
-because the vast majority of problems can be+Older machines might not have the same facility. You will then
-solved quite easily, and a considerable number+need to press either the F2 or ‘Del’ key at boot time to enter the
-involve the same problems recurring again and+system BIOS, and change the boot order from there. You can
-again. In business speak, these are low-hanging+usually find the option under the ‘Boot’ menu, and you will need to
-fruit. And it’s these problems we want to target.+save these changes to be able to boot from the optical drive. This
-You shouldn’t need to be a Linux expert to get+is the same procedure you would use if you needed to boot from
-your machine to boot, or a programmer to play a+an external drive or USB stick, which can be just as useful if you
-movie file. Yet it’s this level of expertise that most+find yourself in an internet cafe or in front of a corporate machine.
-error messages seem to assume of their users. We+ 
-want to demystify these common errors, and+=== '''ERROR: PCI: cannot allocate''' ===
-provide solutions that should help ordinary Linux+ 
-users side-step the problem and get their machine+There are many errors like this, and they mostly occur at boot
-back on track. We’ve chosen areas we think are+time. They all share the same cause – badly behaved power
-the most problematic. These include booting+management. The culprit is something called ACPI, the Advanced
-problems, general software usage, the filesystem,+Configuration and Power Interface. Despite being a standard for
-networking and distro installation.+power management, it has been causing problems for over ten
-We’ve picked a few of the most common errors+years. The trouble is that hardware drivers have a habit of not fully
-from each, and explained what’s happening along+implementing the specification. Whenever your machine’s power
-with the solution. The intention is that even if the+management spins into action, such as when you turn on your
-problems don’t apply to you, you can get an idea+machine, or resume from sleep, certain devices cause problems.
-of how and why Linux error messages might seem+Live CD installations make this problem worse, because they don’t
-arcane and a little intimidating. And hopefully,+have the luxury of probing for exact hardware matches when they
-this will leave you with the knowledge to find a+boot, or including every possible driver for every device, which is
-better solution that might help you to solve your+why this problem often occurs when installing off a Live CD.
-own problems.+ 
 +There’s only one thing you can do – turn off ACPI. You can
 +sometimes do this from your system BIOS, but if not, you’ll need
 +to disable ACPI at boot time. Press Escape when booting to enter
 +the ''Grub'' menu and select the option you normally use. Go down
 +to the line that starts with '''kernel''' and press E to edit the line. At the
 +end of this line add '''acpi=off noapic''', press return and B to start
 +the boot process. You should find that your machine boots without
 +problems, and if you go on to install Linux, your distro should make
 +a better job of choosing the correct drivers for the installation.

Current revision

Distro installation

Every Linux distribution has a different installation routine, and each creates problems. Ubuntu might work for one machine and not for another. A machine with a working Ubuntu installation may not work with Fedora, or OpenSUSE, or Linux Mint, or Mandriva...

ERROR: Can’t boot from CD/DVD

If you’re new to Linux, this is often your first experience of the operating system: you insert your new disc into the drive and restart the machine, only to be greeted by the same operating system you were using before. The problem is that your hard drive has a higher boot priority than your optical drive. Many modern BIOSes include a boot menu from where you can change the priority of your devices on the fly – try pressing the ‘Escape’ key or F12 when you first see something on the screen. From there, you can simply choose to boot from the optical drive.

Older machines might not have the same facility. You will then need to press either the F2 or ‘Del’ key at boot time to enter the system BIOS, and change the boot order from there. You can usually find the option under the ‘Boot’ menu, and you will need to save these changes to be able to boot from the optical drive. This is the same procedure you would use if you needed to boot from an external drive or USB stick, which can be just as useful if you find yourself in an internet cafe or in front of a corporate machine.

ERROR: PCI: cannot allocate

There are many errors like this, and they mostly occur at boot time. They all share the same cause – badly behaved power management. The culprit is something called ACPI, the Advanced Configuration and Power Interface. Despite being a standard for power management, it has been causing problems for over ten years. The trouble is that hardware drivers have a habit of not fully implementing the specification. Whenever your machine’s power management spins into action, such as when you turn on your machine, or resume from sleep, certain devices cause problems. Live CD installations make this problem worse, because they don’t have the luxury of probing for exact hardware matches when they boot, or including every possible driver for every device, which is why this problem often occurs when installing off a Live CD.

There’s only one thing you can do – turn off ACPI. You can sometimes do this from your system BIOS, but if not, you’ll need to disable ACPI at boot time. Press Escape when booting to enter the Grub menu and select the option you normally use. Go down to the line that starts with kernel and press E to edit the line. At the end of this line add acpi=off noapic, press return and B to start the boot process. You should find that your machine boots without problems, and if you go on to install Linux, your distro should make a better job of choosing the correct drivers for the installation.