Thursday, March 13, 2014

Linux Conversion for ASUS S56C (Part 2)

Welcome back!

In Part 1, you saw how to create recovery media for Windows 8.

Sadly, booting to that recovery media (or the install disc for an alternate operating system), isn't trivial.

You might be familiar with older-style systems where you could bring up a boot menu by holding down a hot key on boot, as well as a hot key for booting into the BIOS.

For the ASUS S56C (and possibly other machines as well), that key is Esc. Hold it down as the computer is rebooting (I'm having trouble getting into the BIOS from a cold boot, i.e. from powered-off state, it only seems to work on a reboot. Not sure why yet.)

However, when the menu comes up, you'll notice that you have only two options: The Windows Boot Volume, and "Enter Setup" the BIOS. There are no options to boot from LAN, a USB Key, or an Optical Drive. Very disappointing.

The reason for this is a new form of BIOS called UEFI, and a feature of UEFI known as Secure Boot, which prevents you from starting any unsigned boot loaders with the system loads. The introduction of this has led to a lot of controversy, though it has both good and bad features (think malware which can attack the boot sector). In my option, the most important thing is that it's possible to disable it, or add additional signing keys, so that you can boot a custom operating system. I'll save you the nitty/gritty details (but I encourage you to read them here), and will hop into the details on how to get this thing to boot from something other than the hard drive.

Once you enter the setup, there are four options we need to be concerned with. Sadly, these options are anything but clearly labeled or explained. It took me some time to find the right combination of options to get it working, which was one of my motivations for writing this post.

Security Tab / Disable Secure Boot

1) Much of the documentation you'll read on UEFI/Secure Boot will tell you the first step is to disable the "Secure Boot" option the BIOS. In this System, Secure Boot is called "Secure Boot Control". It's enabled by default, so switch it to "Disabled"

Boot Tab / Enable Legacy BIOS

2) Next, go to the "Boot" tab. The first option you are concerned with here is "Fast Boot". Disable it.
3) The next option is called "Launch CSM". CSM stands for "Compatibility Support Module", as is part of the EFI framework to support legacy BIOS. Change it to Enabled.
4) When you enable Launch CSM, you'll notice the "Fast Boot" option disappears, and a new option called "Launch PXE OpRom" appears. Enable it.

Now, save your changes and reboot. When holding down "Esc", this time you should see new boot options for the optical drive, LAN and USB. Horray! From here, you should be able to boot to the newly created recovery media

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