= Linux kernel =

The part actually called Linux. Some stuff on compiling for it and things it
provides

== Proc ==

/proc is a virtual filesystem provided by the kernel that has info on processes
running and some basic system info. Here are some useful things from it.

* meminfo
 - info about ram usage
* acpi/*
 - info about things that control power (such as laptop lid, power button, etc)
* sys/kernel/*
 - info about the status of the kernel
* crypto
 - encryption algorithms built into the kernel
* uptime
 - system uptime
* fs/*
 - all supported filesystems

== Dev ==

The device virtual file system, located at /dev. Each device is a file and can
be talked to here. Here is some useful info from it

* random
 - random data
* urandom
 - less predictable random data
* zero
 - outputs nothing
* tty*
 - All of the different virual terminals
* cpu/*
 - All cpu cores 
* snd/*
 - All sound devices
* usb/*
 - USB devices
* disk/*
 - All available disks, can be viewed by uuid, partlabel, and more
* mapper/*
 - Where LVM partitions are mounted, including encrypted partitions and drives

== Updating the kernel ==

First be sure to mount the boot parition to /boot

Next copy your .config from the source directory of your previous kernel to
somewhere safe

For gentoo, you'll need to switch your /usr/src/linux symlink using eselect now

Now begins the commands

1) make mrproper
  - make clean with no additional atrtifacts
2) cp /path/to/kernel/config .config
  - Install old config file
3) make olddefconfig
  - copy over old config options to new kernel config
4) make modules_prepare
  - Prepare kernel modules on system
5) make -jX
  - make the kernel! replace X with number of desired threads
6) make modules_install && make install
  - install the new kernel and modules
7) (Gentoo) emerge @module-rebuild
  - Recompile kernel modules to work with the new kenel
8) (Encrypted root only) genkernel --luks --lvm --kernel-config=/path/to/kernel/config initramfs
  - If not on gentoo use distros initramfs build tool. splash adds a splash
    screen and is not required
9) (Encrypte root only) modify /etc/default/grub 
   - On the line with the string "GRUB_CMDLINE_LINUX="
   - In the quotes add 
     - 'dolvm', to enable LVM support
     - 'crypt_root=/dev/{ROOT_DRIVE}', replace {ROOT_DRIVE} with the file for
       the parition with the LVM on it. This tells the initramfs what partition
       to mount as the new root
10) (Optional) Clean up all kernels
  - Go ahead and remove all references in /boot to an older kernel. DO NOT
    delete the current kernel, you may need it in case installing this kernel
    fails!
11) grub-mkconfig -o /boot/grub/grub.cfg
  - Let grub update its config to know that the new kernel exists
12) reboot
  - reboot and hope it worked!

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