The Emergency Kernel - Raspberry Pi User Manual

C H A P T E R 3

The Emergency Kernel

The Linux kernel is the heart of the operating system that drives the Pi . It's responsible for
everything from making sure that you can access your files to allowing programs to talk to
other programs .
When switched on, your Pi will load the normal, default kernel . There's also a second kernel
included in most distributions, which sits unused . This is the emergency kernel, and as the
name suggests, it is typically used only when the normal kernel isn't working .
It's highly unlikely that you'll ever need to boot a Pi using the emergency kernel, but it's
worth learning how to do so just in case . This is especially important if you're upgrading your
kernel or are using a new and potentially poorly tested distribution . Sometimes, newly-
released software can have bugs which aren't spotted before its release . When encountering
strange errors after upgrading, the emergency kernel can be used to narrow down the prob-
lem to the new kernel version .
T R O U B L E S H O O T I N G
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Figure 3-3:
The result of a
successful test
of the network,
using the ping
command