3.11. Troubleshooting

This section covers basic installation troubleshooting of common problems. There are also a few questions and answers for people wishing to dual-boot FreeBSD with Windows®.

3.11.1. If Something Goes Wrong

Due to various limitations of the PC architecture, it is impossible for device probing to be 100% reliable. However, there are a few things to try if it fails.

Check the Hardware Notes document for the version of FreeBSD to make sure the hardware is supported.

If the hardware is supported but still experiences lock-ups or other problems, build a custom kernel to add in support for devices which are not present in the GENERIC kernel. The default kernel assumes that most hardware devices are in their factory default configuration in terms of IRQs, I/O addresses, and DMA channels. If the hardware has been reconfigured, create a custom kernel configuration file and recompile to tell FreeBSD where to find things.

It is also possible that a probe for a device not present will cause a later probe for another device that is present to fail. In that case, the probes for the conflicting driver(s) should be disabled.

Note:

Some installation problems can be avoided or alleviated by updating the firmware on various hardware components, most notably the motherboard BIOS. Most motherboard and computer manufacturers have a website where upgrade information may be located.

Most manufacturers strongly advise against upgrading the motherboard BIOS unless there is a good reason for doing so, such as a critical update. The upgrade process can go wrong, causing permanent damage to the BIOS chip.

3.11.2. Using Windows® Filesystems

At this time, FreeBSD does not support file systems compressed with the Double Space™ application. Therefore the file system will need to be uncompressed before FreeBSD can access the data. This can be done by running the Compression Agent located in the Start> Programs > System Tools menu.

FreeBSD can support MS-DOS® file systems (sometimes called FAT file systems). The mount_msdosfs(8) command grafts such file systems onto the existing directory hierarchy, allowing the file system's contents to be accessed. The mount_msdosfs(8) program is not usually invoked directly; instead, it is called by the system through a line in /etc/fstab or by using mount(8) with the appropriate parameters.

A typical line in /etc/fstab is:

/dev/ad0sN  /dos  msdosfs rw  0	0

Note:

/dos must already exist for this to work. For details about the format of /etc/fstab, see fstab(5).

A typical call to mount(8) for a FAT filesystem looks like:

# mount -t msdosfs /dev/ad0s1 /mnt

In this example, the FAT filesystem is located on the first partition of the primary hard disk. The output from dmesg(8) and mount(8) should produce enough information to give an idea of the partition layout.

Note:

FreeBSD may number FAT partitions differently than other operating systems. In particular, extended partitions are usually given higher slice numbers than primary partitions. Use fdisk(8) to help determine which slices belong to FreeBSD and which belong to other operating systems.

3.11.3. Troubleshooting Questions and Answers

3.11.3.1. My system hangs while probing hardware during boot or it behaves strangely during install.
3.11.3.2. When booting from the hard disk for the first time after installing FreeBSD, the kernel loads and probes hardware, but stops with messages like:
3.11.3.3. When booting from the hard disk for the first time after installing FreeBSD, the Boot Manager prompt just prints F? at the boot menu and the boot will not go any further.
3.11.3.4. The system finds the ed(4) network card but continuously displays device timeout errors.
3.11.3.5. When sysinstall(8) is usedin an Xorg terminal, the yellow font is difficult to read against the light gray background. Is there a way to provide higher contrast for this application?

3.11.3.1.

My system hangs while probing hardware during boot or it behaves strangely during install.

FreeBSD makes extensive use of the system ACPI service on the i386, amd64, and ia64 platforms to aid in system configuration if it is detected during boot. Unfortunately, some bugs still exist in the ACPI driver and various system motherboards. The use of ACPI can be disabled by setting hint.acpi.0.disabled in the third stage boot loader:

set hint.acpi.0.disabled="1"

This is reset each time the system is booted, so it is necessary to add hint.acpi.0.disabled="1" to /boot/loader.conf to make this change permanent. More information about the boot loader can be found in Section 13.1, “Synopsis”.

3.11.3.2.

When booting from the hard disk for the first time after installing FreeBSD, the kernel loads and probes hardware, but stops with messages like:

changing root device to ad1s1a panic: cannot mount root

What is wrong?

This can occur when the boot disk is not the first disk in the system. The BIOS uses a different numbering scheme to FreeBSD, and working out which numbers correspond to which is difficult to get right.

If this occurs, tell FreeBSD where the root filesystem is by specifying the BIOS disk number, the disk type, and the FreeBSD disk number for that type.

Consider two IDE disks, each configured as the master on their respective IDE bus, where FreeBSD should be booted from the second disk. The BIOS sees these as disk 0 and disk 1, while FreeBSD sees them as ad0 and ad2.

If FreeBSD is on BIOS disk 1, of type ad and the FreeBSD disk number is 2, this is the correct value:

1:ad(2,a)kernel

Note that if there is a slave on the primary bus, the above is not necessary and is effectively wrong.

The second situation involves booting from a SCSI disk when there are one or more IDE disks in the system. In this case, the FreeBSD disk number is lower than the BIOS disk number. For two IDE disks and a SCSI disk, where the SCSI disk is BIOS disk 2, type da, and FreeBSD disk number 0, the correct value is:

2:da(0,a)kernel

This tells FreeBSD to boot from BIOS disk 2, which is the first SCSI disk in the system. If there is only IDE disk, use 1: instead.

Once the correct value to use is determined, put the command in /boot.config using a text editor. Unless instructed otherwise, FreeBSD will use the contents of this file as the default response to the boot: prompt.

3.11.3.3.

When booting from the hard disk for the first time after installing FreeBSD, the Boot Manager prompt just prints F? at the boot menu and the boot will not go any further.

The hard disk geometry was set incorrectly in the partition editor when FreeBSD was installed. Go back into the partition editor and specify the actual geometry of the hard disk. FreeBSD must be reinstalled again from the beginning with the correct geometry.

For a dedicated FreeBSD system that does not need future compatibility with another operating system, use the entire disk by selecting A in the installer's partition editor.

3.11.3.4.

The system finds the ed(4) network card but continuously displays device timeout errors.

The card is probably on a different IRQ from what is specified in /boot/device.hints. The ed(4) driver does not use software configuration by default, but it will if -1 is specified in the hints for the interface.

Either move the jumper on the card to the configuration setting or specify the IRQ as -1 by setting the hint hint.ed.0.irq="-1". This tells the kernel to use the software configuration.

Another possibility is that the card is at IRQ 9, which is shared by IRQ 2 and frequently a cause of problems, especially if a VGA card is using IRQ 2. Do not use IRQ 2 or 9 if at all possible.

3.11.3.5.

When sysinstall(8) is usedin an Xorg terminal, the yellow font is difficult to read against the light gray background. Is there a way to provide higher contrast for this application?

If the default colors chosen by sysinstall(8) make text illegible while using x11/xterm or x11/rxvt, add the following to ~/.Xdefaults to get a darker background gray: XTerm*color7: #c0c0c0

All FreeBSD documents are available for download at http://ftp.FreeBSD.org/pub/FreeBSD/doc/

Questions that are not answered by the documentation may be sent to <freebsd-questions@FreeBSD.org>.
Send questions about this document to <freebsd-doc@FreeBSD.org>.