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Boot Linux Without An Initramfs

So you think you always need an initramfs to boot your Linux system. Not true and I will show you how. For example, here is my GRUB2 (/boot/grub2/grub.cfg) configuration file for Fedora 17: menuentry ‘Fedora Linux, no initramfs’ { set root=’hd0,msdos1′ linux /vmlinuz-3.3.4-5.fc17.i686.PAE rootfstype=ext4 root=/dev/sda2 rd.md=0 rd.lvm=0 rd.dm=0 SYSFONT=True KEYTABLE=us rd.luks=0 LANG=en_US.UTF-8 } Note there is no line specifying an initramfs! I was not aware that this was possible until I saw it demonstrated by Harald Hoyer. By the way, in case you were wondering, yes I manually edit my GRUB2 configuration file rather than using the numerous crazy GRUB2

Tickless Linux Kernels

Linux now uses a tickless kernel by default. Before the advent of the tickless kernel, idle kernels woke themselves up (interrupted) at a rate of 100 Hz, 250 Hz or 1000 Hz, depending on how they were configured, to look for something to do. When interrupted, the kernel queried the CPU about the processes that it was executing, and used the results for process accounting and load balancing. This is known as the timer tick and the kernel performed this interrupt regardless of CPU power state. The practical result of this design meant that on systems implementing idle CPU power

UEFI Memory V E820 Memory

In this post I discuss the differences between how UEFI hands off memory to the Linux Kernel and how old-fashioned BIOSes handled off memory via E820.