Introduction
To determine which guides are relevant to your problem see the symptom based debugging guide.
Kernel Debugging Scenarios
Backlight -- How to debug issues related to backlight brightness control
Hibernate/Resume -- Help debugging kernel hibernate/resume problems
High Temperatures -- How to debug thermal issues and/or fan related problems
Hotkeys -- How to debug non-working hotkeys
Kernel Boot -- debugging Kernel boot issues
Kernel Oops -- Analyzing Kernel Oopses
Suspend/Resume -- Help debugging kernel suspend/resume problems
Trace scheduling while atomic -- How to gather a trace to help debug "scheduling while atomic" bugs
Update Errors -- Debugging common errors seen when updating/upgrading
Kernel Debugging Guides
ACPI -- debugging ACPI (Advanced Configuration and Power Interface)
BIOS -- Debugging BIOS issues on Ubuntu (DSDT, Reboot, Suspend/Resume)
IRQ -- debugging interrupt related issues
Sound -- Basic troubleshooting tips for debugging sound problems
System Crash -- Tips for gather information regarding system crashes and lockups
Kernel Debugging Tools/Information
Firmware -- All about firmware and how to debug firmware loading issues
Kernel Debugging Tricks -- Some kernel debugging tricks and tips
linux-crashdump -- How to use linux-crashdump to capture a kernel oops/panic
Mainline Kernel Builds -- How to use mainline kernels for debugging
Netconsole -- Configuring console over network using netconsole
Systemtap -- Introduction to Systemtap for reboot free, dynamic instrumentation
Ubuntu Kernel Team PPA -- Instructions on how to use the Ubuntu Kernel Team's PPA, as well as using a specific kernel developer's PPA
Ubuntu to mainline kernel mapping -- A table of Ubuntu releases and which mainline version they are based on, including the current release pocket assignments
USB -- How to debug USB problems
View early printk via USB -- How to view early printk messages using USB debug
Voodoo -- Q&A for strange symptoms and how to debug
Kernel Debugging with QEMU/KVM -- How to debug a kernel running inside a QEMU/KVM instance
Links
Kernel Newbies Debug -- Debugging the Linux Kernel