In episode #19 of the BYOB podcast we discussed the Unified Extensible Firmware Interface or UEFI. Read on for an overview of the subject and some great information on UEFI.
The BYOB podcast can be found on iTunes or at:
http://homeservershow.com/byob-episode-19.html
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What is UEFI?
Unified Extensible Firmware Interface (UEFI) is interface between the pre-boot environment and the starting of the operating system. UEFI is important because it will eventually lead to changes in BIOS, operating systems and add-in cards.
Image From Wiki
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The Expected Result – Faster Boot Times
Intel tells us we could have EFI boot times (the time prior to the OS load start) reduced from 15 seconds to the sub-2-second range. Really? Yes. This means you could see the Windows logo in three seconds and have Windows running in about 15 seconds. Sweet!
For more information, read this short white paper (pdf) from Intel on “Fastboot BIOS” on an Atom platform.
Fastboot BIOS
At the conclusion they say:
Achieving a sub-2 second boot time with EFI BIOS is not difficult. While many of the methods used are specific to embedded markets (removal of features), several other methods are optimizations useful for all BIOS markets. From this investigation, it seems likely that sub-1second boot time is attainable without changing the overall architecture or features of the BIOS.
That is all I need to hear.
Lets set this pig on fire!
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BIOS AND POST
To understand UEFI better let us take a quick look at what happens once you press start your PC.
Image From Wiki
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Once you press the power button, the BIOS, also know as firmware stored on your motherboard, checks that a hard drive, video card, keyboard, mouse etc. are all present and accounted for. This first system configuration is called POST (Power on Self Test). It verifies that they are all working and installed properly and then starts bootstrapping to the hard drive. Over the years, bootstrapping was eventually just shortened to booting or boot. Anyway, the BIOS firmware starts the load of the operating system (boot loader) into the memory storage from the OS drive.
After this first 10 seconds or so you then see the operating system loading status on the monitor, typically a Windows logo, and less than a minute later you are up and running. BIOS had been doing the same thing since the IBM PC ATs and the settings for the BIOS are stored in nonvolatile memory on the motherboard. It used to be called CMOS BIOS because it needed the battery to store the information. Modern PCs use either EEPROM or flash memory and the battery is only for the clock or to reset the BIOS is some systems.
So, now that we understand BIOS and what happens, why do we need to change it?
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Master Boot Record – The 2.2TB Limit
Current BIOS, with Master Boot Record partitioning, uses 32-bit values to describe the starting offset and length of a partition. The Master Boot Record (MBR) is the partition scheme. The MBR is not in a partition itself but is a data table that contains the primary partition entries for the partitions. The design dates back to the 80’s and can only keep track of four partitions by design. No one knew back then we would outgrow these storage limits!
All of the partition data is stored as 32-bit so the math on this value limits the disk space. 232 times the 512 bytes per sector gives us 2,199,023,255,552 bytes for those playing the home game.
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Current Windows 7 PCs (and almost every other Windows PC) boots from the MBR disk through the BIOS.
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These MBR drive partition limits are why we need to be informed on the new technology and how it affects us.
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