FreeBSD Handbook
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# 2.10 Troubleshooting

The following section covers basic installation troubleshooting, such as common problems people have reported.

## 2.10.1 What to Do If Something Goes Wrong

Due to various limitations of the PC architecture, it is impossible for probing to be 100% reliable, however, there are a few things you can do if it fails.

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

If your hardware is supported and you still experience lock-ups or other problems, you will need to build a custom kernel. This will allow you to add in support for devices which are not present in the `GENERIC` kernel. The kernel on the boot disks is configured assuming that most hardware devices are in their factory default configuration in terms of IRQs, IO addresses, and DMA channels. If your hardware has been reconfigured, you will most likely need to edit the kernel configuration 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. Motherboard firmware is usually referred to as the BIOS. Most motherboard and computer manufacturers have a website for upgrades and upgrade information.

> Manufacturers generally advise against upgrading the motherboard BIOS unless there is a good reason for doing so, like a critical update. The upgrade process can go wrong, leaving the BIOS incomplete and the computer inoperative.

## 2.10.2 Troubleshooting Questions and Answers

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

2.10.2.1. 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 both the ACPI driver and within system motherboards and BIOS firmware. ACPI can be disabled by setting the `hint.acpi.0.disabled` hint 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 the file `/boot/loader.conf`. More information about the boot loader can be found in Section 13.1.

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