Both of these programs are examples of low-level software that runs when the computer starts up before the operating system loads. UEFI is a newer solution, it supports larger hard drives, it boots faster, it's more secure - and, very conveniently, it has a graphical interface and mouse support.
Some newer computers shipped with UEFI still refer to it as "BIOS" so as not to confuse a user accustomed to traditional PC BIOSes. But even if you see it mentioned, know that your new computer will most likely be equipped with UEFI, not BIOS.
What is a BIOS?
BIOS is Basic Input-Output system, basic input-output system. This is a low-level program stored on a chip in your computer's motherboard. The BIOS is loaded when the computer is turned on and is responsible for waking up its hardware components, making sure that they are working correctly, and then launching the bootloader that starts the Windows operating system or any other operating system you have installed.
On the BIOS setup screen, you can change many options. Computer hardware configuration, system time, boot order. This screen can be called up at the beginning of the computer boot by pressing a certain key - it is different on different computers, but Esc, F2, F10, Delete keys are often used. When you save a setting, you store it in the motherboard's memory. When the computer boots up, the BIOS will set it up as specified in the saved settings.
Before loading the operating system, the BIOS goes through POST, or Power-On Self Test, after power-on. It checks that the hardware is configured correctly and that it works. If something is wrong, you will see a series of error messages on the screen or hear a mysterious squeak from the system unit. What exactly the beeps mean is described in the instructions for the computer.
When the computer boots, at the end of POST, the BIOS looks for the Master Boot Record, or MBR - Master Boot Record. It is stored on the boot device and is used to start the OS bootloader.
You may also have seen the abbreviation CMOS, which stands for Complementary Metal-Oxide-Semiconductor - a complementary metal-oxide-semiconductor structure. It refers to the memory where the BIOS stores various settings. Its use has become obsolete, since this method has already been replaced by flash memory (also called EEPROM).
Why is the BIOS outdated?
The BIOS has been around for a long time and has evolved little. Even MS-DOS computers released in the 1980s had a BIOS.Of course, over time, the BIOS still changed and improved. Its extensions were developed, in particular, ACPI, Advanced Configuration and Power Interface (Advanced Configuration and Power Management Interface). This allowed the BIOS to more easily configure devices and more advanced power management, such as hibernation. But the BIOS hasn't evolved as much as other computer technologies since MS-DOS.
The traditional BIOS still has serious limitations. It can only boot from hard drives with a maximum capacity of 2.1 TB. Now 3 TB disks are already ubiquitous, and a computer with a BIOS will not boot from them. This is a BIOS MBR limitation.
The BIOS must work in 16-bit processor mode and only 1 MB of memory is available to it. It has problems initializing multiple devices at the same time, which leads to a slow boot process, during which all hardware interfaces and devices are initialized.
The BIOS is long overdue for a replacement. Intel began work on the Extensible Firmware Interface (EFI) back in 1998. Apple chose EFI when they switched to the Intel architecture on their Macs in 2006, but other manufacturers didn't follow suit.
In 2007, Intel, AMD, Microsoft, and PC manufacturers agreed on a new Unified Extensible Firmware Interface (UEFI) specification, a unified extensible firmware interface. This is an industry standard maintained by the UEFI forum and is not just Intel-specific. UEFI support in Windows was introduced with Windows Vista Service Pack 1 and Windows 7. Most computers you can buy today use UEFI instead of BIOS.
How UEFI Replaces and Improves the BIOS
UEFI replaces the traditional BIOS on PCs. There is no way to change the BIOS to UEFI on an existing PC. You need to buy hardware that supports UEFI. Most UEFI versions support BIOS emulation so you can install and run legacy OSes that expect BIOS instead of UEFI - so they are backwards compatible.
The new standard bypasses BIOS restrictions. UEFI firmware can boot from drives larger than 2.2 TB - the theoretical limit for them is 9.4 zettabytes. That's about three times the amount of data on the Internet today. UEFI supports such volumes due to the use of GPT partitioning instead of MBR. It also has a standardized boot process and runs EFI executables instead of MBR code.
UEFI can run in 32-bit or 64-bit modes, and its address space is larger than that of the BIOS, which means it boots faster. It also means that the UEFI setup screens can be made prettier than the BIOS, including graphics and mouse support. But this is optional. Many computers still run text-mode UEFI, which looks and works just like the old BIOS screens.
There are many other features built into UEFI. It supports Secure Boot, in which you can check that no malware has changed the boot of the OS. It can support network operation, which allows remote configuration and debugging. In the case of the traditional BIOS, you had to sit right in front of the computer to set up the computer.
And it's not just a BIOS replacement. UEFI is a small operating system that runs on top of PC firmware, so it's capable of much more than BIOS. It can be stored in flash memory on the motherboard or loaded from a hard drive or network.
Different computers have different interface and UEFI properties. It all depends on the manufacturer of the computer, but the basic features are the same for everyone.
How to Access UEFI Settings on a Modern PC
If you are a regular user, you will not notice the transition to a computer with UEFI. Booting and shutting down your computer will be faster, and you will also have access to drives larger than 2.2 TB.But the procedure for accessing the settings will be slightly different. You may need the Windows boot menu to access the UEFI settings screen. PC manufacturers did not want to slow down the fast boot of the computer by waiting for a keystroke. But we also met such UEFIs in which manufacturers left the ability to enter the settings in the same way as in the BIOS - by pressing a key during boot.
UEFI is a big update, but it happened quietly. Most PC users won't notice it and don't need to worry about their new PC using UEFI instead of the regular BIOS. PCs will simply perform better and support more modern hardware and features.
A more detailed explanation of the differences in the UEFI boot process can be found in
Most modern computers, instead of the usual primary input / output system, are equipped with the latest control tool, called UEFI. What it is, not yet known to all users of computers and laptops. In the following, some important aspects related to this development will be considered. In addition, we will briefly touch on issues related to installing operating systems through this interface using bootable USB media, and also determine how to disable UEFI if using this system is inappropriate for some reason. But first, let's look at the primary understanding of what kind of system it is.
UEFI: what is it?
Many users are accustomed to the fact that in order to configure the primary parameters of the computer system, even before the OS starts, you need to use the BIOS. In fact, the UEFI mode, which is used instead of the BIOS, is almost the same, but the system itself is built on the basis of a graphical interface.
When loading this system, which, by the way, many call a kind of mini-OS, the fact of mouse support and the ability to install a regional language for the interface immediately attract attention. If you go further, you will notice that, unlike the BIOS, UEFI can work with support for network devices and display the optimal operating modes for some components of the installed hardware.
Some call this system a dual term - BIOS UEFI. Although this does not contradict the logic of software and hardware, nevertheless, such a definition is somewhat incorrect. Firstly, UEFI is developed by Intel Corporation, and BIOS systems are developed by many other brands, although they do not differ radically from each other. Secondly, BIOS and UEFI operate on slightly different principles.
The main differences between UEFI and BIOS
Now another look at UEFI. What this is in a clearer sense can be determined by finding out the differences between this system and the BIOS. It is believed that UEFI is positioned as a kind of alternative to the BIOS, the support of which is now announced by many motherboard manufacturers. But the differences are best considered on the basis of the minuses of obsolete BIOS systems.
The very first difference is that the BIOS's primary input/output systems do not allow working correctly with hard drives of 2 TB or more, which means that the system does not have the ability to fully utilize the disk space.
The second point is that BIOS systems are limited to working with disk partitions, while UEFI supports up to 128 partitions, which is made possible thanks to the GPT partition table.
Finally, UEFI implements completely new security algorithms, which completely eliminates the bootloader substitution at the start of the main OS, preventing even the effects of viruses and malicious codes, and provides a choice of the bootable operating system without using specific tools inside the bootloaders of the OS itself.
A bit of history
This is the UEFI system. What it is is already somewhat clear. Now let's see where it all began. It is a mistake to think that UEFI is a relatively recent development.
The creation of UEFI and the universal interface began in the early 90s. As it turned out then, for Intel server platforms, the capabilities of standard BIOS systems were not enough. Therefore, a completely new technology was developed, which was first implemented in the Intel-HP Itanium platform. At first it was called the Intel Boot Initiative, and was soon renamed the Extensible Firmware Interface or EFI.
The first modification of version 1.02 was introduced in 2000, version 1.10 was released in 2002, and since 2005, the then-formed alliance of several companies, called the Unified EFI Forum, began to develop the new development, after which the system itself became known as UEFI. Today, among the developers, you can meet many famous brands, such as Intel, Apple, AMD, Dell, American Megatrends, Microsoft, Lenovo, Phoenix Technologies, Insyde Software, etc.
UEFI security system
Separately, it is worth dwelling on the mechanisms of the protection system. If anyone does not know, today there is a special class of viruses that are able to prescribe their own malicious codes when embedded in the microcircuit itself, changing the initial algorithms of the I / O system, which leads to the possibility of launching the main operating system with extended management rights. This is how viruses can gain unauthorized access to all OS components and controls, not to mention user information. Installing UEFI completely eliminates the occurrence of such situations by implementing a secure boot mode called Secure Boot.
Without going into technical aspects, it is only worth noting that the security algorithm itself (secure boot) is based on the use of special certified keys supported by some well-known corporations. But, for some reason, it is believed that this option is supported only by Windows 8 and higher operating systems, as well as some modifications of Linux.
Why is UEFI better than BIOS?
The fact that UEFI surpasses BIOS in its capabilities is noted by all experts. The fact is that the new development allows you to solve some problems even without loading the operating system, the start of which, by the way, when the optimal mode of operation of the main "iron" components such as a processor or RAM is set, is much faster. According to some reports, the same Windows 8 boots within 10 seconds (however, this indicator is clearly conditional, since you need to take into account the general hardware configuration).
However, UEFI support also has a number of undeniable advantages, among which are the following:
- simple intuitive interface;
- support for regional languages and mouse control;
- work with disks 2 TB and above;
- the presence of its own bootloader;
- the ability to work on processors with x86, x64 and ARM architecture;
- the ability to connect to local and virtual networks with Internet access;
- the presence of its own system of protection against the penetration of malicious codes and viruses;
- simplified update.
Supported operating systems
Unfortunately, not all operating systems support UEFI. As already mentioned, basically such support is declared for some modifications of Linux and Windows, starting from the eighth version.
Theoretically, you can install Windows 7 (UEFI recognizes the installation distribution). But no one will give a full guarantee that the installation will be completed successfully. In addition, in the case of using Windows 7, the UEFI interface and all the related features of the new system will simply remain unclaimed (and often unavailable). Thus, it is not advisable to install this particular system on a computer or laptop with UEFI support.
Features of Secure Boot Boot Mode
As mentioned above, the secure boot system is based on the use of certified keys to prevent viruses from entering. But such certification is supported by a limited number of developers.
When the operating system is reinstalled via UEFI, there will be no problems provided that the installed system is as close as possible to the original installed earlier. Otherwise (which is not uncommon), a ban on installation may be issued. However, there is also a way out, since the Secure Boot mode itself can be disabled in the settings. This will be discussed separately.
Nuances of access and UEFI settings
There are quite a lot of UEFI versions themselves, and different computer equipment manufacturers install their own options for starting the primary system. But sometimes, when trying to access the interface, problems can arise, such as the main settings menu is not displayed.
In principle, for most computers and laptops with UEFI support, you can use a universal solution - pressing the Esc key when logging in. If this option does not work, you can use the native Windows tools.
To do this, you need to enter the settings section, select the recovery menu and in the line of special boot options, click on the link "restart now", after which several start options will appear on the screen.
As for the basic settings, they practically do not differ from standard BIOS systems. Separately, we can note the presence of the BIOS emulator mode, which in most cases can be called either Legacy or Launch CSM.
In addition, it is worth paying attention to the fact that when switching to Legacy mode, at the first opportunity, you should re-enable the UEFI settings, since the operating system may not boot. By the way, the differences between different versions of UEFI are that some provide a hybrid launch mode for either the BIOS emulator or UEFI, while others do not have such an opportunity when working in normal mode. Sometimes this may also apply to the inability to disable Secure Boot.
UEFI bootable flash drive: prerequisites for creating
Now let's see how to create a bootable USB drive for the subsequent installation of the operating system using the UEFI interface. The first and most important condition is that the UEFI bootable USB flash drive must have a capacity of at least 4 GB.
The second problem concerns the file system. As a rule, Windows systems format removable drives using NTFS by default. But UEFI USB drives with file systems other than FAT32 are not recognized. Thus, at the first stage, formatting should be done using this parameter.
Formatting and burning a distribution image
Now the most important moment. Formatting is best done from the command line (cmd) launched with administrator rights.
In it, the diskpart command is first entered, after which the list disk line is written, and the desired device is selected with the select disk N command, where N is the serial number of the USB flash drive.
Further, for complete cleaning, the clean line is used, and then the primary partition is created by the create partition primary command, which is activated by the active command. After that, the list volume line is used, the flash drive is selected with the select volume N line (the above partition serial number), and then the start of the formatting process is activated with the format fs=fat32 command. At the end of the process, the assign command can assign a specific character to the media.
After that, an image of the future system is written to the media (you can use either regular copying or creating a bootable USB flash drive in programs like UltraISO). When rebooting, the desired media is selected, and the OS is installed.
Sometimes a message may appear stating that installation to the selected MBR partition is not possible. In this case, you need to go to the UEFI boot priority settings. There will be displayed not one, but two flash drives. The download must be started from the device in the name of which there is no EFI abbreviation. This eliminates the need to convert MBR to GPT.
UEFI firmware update
As it turns out, updating the UEFI firmware is much easier than performing similar operations for the BIOS.
It is enough just to find and download the latest version on the official website of the developer, and then run the downloaded file as an administrator in a Windows environment. The update process will take place after the system is rebooted without user intervention.
Disable UEFI
Finally, let's see how to disable UEFI, for example, for cases where booting from removable media is impossible only because the device itself is not supported.
First you need to go to the Security section and disable the Secure Boot mode (if possible) by setting the Disabled parameter for it. After that, in the Boot boot menu, in the Boot Priority priority line, set the Legacy First value. Next, from the list, you need to select the device that will be the first to boot (hard drive) and exit the settings, after saving the changes (Exit Saving Changes). The procedure is completely similar to the BIOS settings. Instead of menu commands, you can use the F10 key.
Brief summary
That's briefly all about the UEFI systems that have replaced the BIOS. They have a lot of advantages, as you can see. Many users are especially pleased with the graphical interface with native language support and the ability to control using the mouse. However, fans of the seventh version of Windows will have to disappoint. Its installation on UEFI-enabled computer systems looks not only impractical, but sometimes it becomes completely impossible. Otherwise, the use of UEFI looks very simple, not to mention some additional features that can be used even without loading the operating system.
UEFI (Unified Extensible Firmware Interface) technology, like BIOS, is a computer firmware interface that provides communication between it and the operating system. Like BIOS, the UEFI interface (also referred to in Russian-language computer journalism as UEFI) is used to initialize the computer's hardware components and start the operating system stored on the hard drive.
UEFI positioning scheme in the generalized structure of the interaction of PC components.
The BIOS reads information from the first sector of the hard drive, which contains the Master Boot Record (MBR), and selects the boot device where the operating system resides. Because the BIOS is a very old system, dating back to the mid-1970s, it still runs in 16-bit mode. This circumstance limits the amount of information that can be read from the system ROM (computer read-only memory).
UEFI performs the same task but does it in a slightly different way. It stores all information about the initialization and booting of the system in a special file located on the hard disk in a special ESP (EFI System Partition) section. In addition, ESP contains boot programs for the operating system installed on the computer.
The process of booting a computer based on UEFI and emulating a traditional Legacy BIOS
UEFI is intended to be a complete replacement for the BIOS in the future and offers many new features and improvements that cannot be implemented in the BIOS:
- No restrictions on the volume of sections and their number. BIOS uses the Master Boot Record (MBR) to store information about the hard disk, while UEFI uses the so-called GPT (GUID partition table). The main difference between them is that MBR uses 32-bit elements, which allows the system to have only 4 physical disk partitions, and each partition can be no more than 2 terabytes in size. As for GPT, it has 64-bit elements, which allows the system to have up to 128 partitions up to a zettabyte (1021 bytes) in size.
- Speed and performance. Since the UEFI technology is platform independent, it can reduce boot time and increase the speed of the computer, especially if large hard drives are installed in the system.
- Safety. The biggest advantage of UEFI over BIOS is security. It is implemented using Secure Boot technology (secure startup) supported by the Windows 8 operating system. Since Secure Boot has the ability to request a digital signature from boot programs, the UEFI interface allows only authenticated drivers and services to be used during boot. Secure Boot controls the boot process until the operating system is fully loaded. This ensures that no malware enters the computer during boot.
- Backward compatibility. For backward compatibility, most UEFI implementations on PC architectures also support Legacy BIOS mode for MBR disks. To do this, UEFI has a CSM (Compatibility Support Module, Compatibility Support Module) function. In the case of an MBR disk, booting is performed in the same mode as in BIOS-based systems. It is also possible to boot BIOS-based systems from disks that have GPT.
- Network boot support. UEFI can boot over the network using Preboot eXecution Environment (PXE) technology. This technology supports major network protocols such as IPv4 and IPv6, UDP, DHCP, and TFTP. Booting from boot images stored in network storages is also supported.
- Download manager. The UEFI standard defines the boot manager as a tool designed to boot the operating system and all necessary drivers. Operating system loaders are stored in files that can be accessed by the firmware. UEFI supports FAT32 file systems, as well as FAT16 and FAT12 for removable media. UEFI is independent of boot sectors, although ESP allocates space for them for backwards compatibility. Bootloaders are automatically detected by UEFI software, allowing booting from removable media.
History of technology
EFI BIOS technology was originally developed by Intel. The UEFI standard is currently being developed by the UEFI Forum.
The initial motivation for the development of EFI was BIOS limitations, such as 16-bit processor mode, 1 MB of addressable memory space, which was unacceptable for serious server platforms such as Itanium. An attempt to fix these problems was originally called the Intel Boot Initiative in 1998 and later renamed EFI.
In 2005, Intel put the EFI standard on hold at version 1.10 and handed it over to the Unified EFI Forum, which evolved the standard into a UEFI version. At the same time, the owner of the original EFI BIOS standard continues to be Intel, which issues licenses for products based on EFI technology. UEFI 2.1 was released in January 2007 and adds data encryption, network authentication, and User Interface Architecture technology. The current version of the UEFI 2.4 standard was adopted in July 2013.
Criticism of UEFI
UEFI is sometimes criticized, in particular by advocates of information rights. For example, computer expert Ronald G. Munnich, one of the developers of the alternative open source boot technology Coreboot, denounces EFI as an attempt to limit a user's ability to fully control their computer. In addition, he believes that this technology does not solve any of the long-standing problems of the traditional BIOS, in particular, the need for two drivers - one for the firmware, the other for the operating system.
Conclusion
UEFI is a technology that has both many advantages and disadvantages. To date, it is not yet ubiquitous and is not supported by all computers and other devices. Having a boot manager built into UEFI means that there is no need for separate bootloaders. In addition, this technology can work in conjunction with the BIOS (in compatibility mode - Legacy BIOS) and independently. At the same time, the BIOS can still be used where it is not necessary to store large amounts of data, and the security problem is not extremely relevant.
UEFI(unifiedExtensibleFirmwareinterface, EFI)- software, interface interlayer between firmware motherboard and O operating room With system.
Created on the initiative Intel and originally created For first systems HP-Itanium V 1990 -x, while the original name was IBI, later became EFI, and then UEFI. Developed as replacement, which did not change since the time PC, supported only 16 bit addressing, maximum 1 MB ROM and other hardware restrictions.
IN 2005 year, Intel corp. passed the initiative development and promotion EFI– UEFI Forum. The transmitted version was version 1.10, and the system itself was renamed to UEFI (United EFI).
Latest version in free access – 2.1 (dated - Jan. 7, 2007 ), which had improved encryption, network configuration, expanded custom interface and many bugs fixed. The latest version is labeled 2.3.1 and was released in April 2011 of the year. It has added support for all types existing architectures and popular processors improved interface, functionality, stability And number of settings that the user can use.
UEFI - contains data tables about devices boot services, services. The firmware itself already contains schemes for working with volume over 2TB, fast loading, CPU drivers, add-ons for Internet networks, add-ons for recognition processor architectures And controllers. UEFI much more functional And more comfortable PC BIOS, while supporting such functions BIOS-but as ACPI, SMBIOS, since these functions do not require 16 -bit addressing.
Large hard drives.
UEFI It has compatibility with a new hard disk partitioning system GPT(GUIDPartition table) , wherein No many restrictions embedded in DOS MBR. This allows use with UEFIhard disks, volume over 2.2 TB to disk, and mark each of them on more than 4 download areas. For now ( 2011 ), use hard disks with a capacity over 2.2 TB to disk with UEFI, may 64-bit O operating rooms With systems, beginning with Windows Vista And Windows Server 2008, and OS Windows Server 2003 And Windows XP, intended for Itanium systems. Unix- similar operating systems have not yet provided themselves with support UEFI.
Processor and hardware compatibility.
Beginning since version 2.3, supported processor architectures x86, x86-64, . Unlike 16 -ty bit BIOS, UEFIcan address much more memory, how 1 MB, since it is built on 32 —bit addressing. This allows you to do comfortable And beautiful interface, expand functional, embed basic drivers For fast boot OS.
Specification UEFI provides an architecturally independent driver environment EFI Byte Code (EBC). This environment can work emulate any architecture, for initial launch. This is achieved due to the fact that device firmware (Firmware) under UEFI, already include interpreters for easy and correct recognition by the system EBC.
IN UEFI own download manager And choice of operating systems, which allows you not to use the bootloader of operating systems and improves stability.
Extended functionality.
UEFI can be used as an operating system, with many features in critical cases when the main one is not loading. It all depends on type UEFI And its elaboration motherboard manufacturers. For example, using UEFI Can go online, set up network connection, play music And video, see photo and even edit them, perhaps update all firmware devices over the Internet and much more.
EFI gradually being replaced UEFI because of lack of support and an increase in the number of systems using x64 addressing.
UEFI controversy.
Main criticism occurs due to causeless, not carrying any significant advantages complications loading systems. Also criticized closed system, which can lead to inability to install O operating With system not provided by the manufacturer. In this case, this is a road to nowhere, since most manufacturers and market leaders, on the contrary, are striving for unification And openness program code.
In order to compatibility with old hardware solutions, manufacturers OS, more likely keep compatibility of their products with older systems on PC-BIOS. Otherwise it may badly affect on sales, and slowing down the growth of the market as a whole. PC hardware manufacturers will probably do the same for the sake of compatibility with previous OS.
The mass transition to UEFI (Unified Extensible Firmware Interface) has already begun. Microsoft requires this interface to be used on all computers that will ship with Windows 8. More specifically, we are talking about UEFI with Secure Boot. At the same time, only G8 can work on such PCs without problems: neither Windows XP nor G7 can be installed on a UEFI machine without additional manipulations. You won't be able to boot from a Linux Live or Windows flash drive either. What exactly can happen if you try to start from an installation flash drive on a Sony VAIO laptop is shown in the picture above. And the problems with UEFI do not end there. Each hardware manufacturer configures UEFI at its own discretion, thereby creating unnecessary difficulties for the user. Lenovo's IdeaPad laptop couldn't recognize the same flash drive as bootable media at all. At the same time, there is nothing to blame Lenovo for: the fact is that the bootable flash drive is formatted in the NTFS file system, and UEFI does not support booting from such media. If you connect the same drive to an HP EliteBook laptop, it will boot without problems and allow you to install Windows. The problem is that all the data that was on the EliteBook disk would be deleted after installation.
Everyone configures in their own way
Are you confused? No wonder: UEFI with the Secure Boot function sets new rules for installing and loading operating systems, and hardware manufacturers interpret these rules in their own way, which creates additional difficulties for the user. Therefore, within the framework of this article, we set ourselves the goal of eliminating the confusion around UEFI. Using laptops from major manufacturers as examples, we will explain how UEFI works, what role the Secure Boot function plays, how to get around the "traps" set by the new interface, and what is needed in order to use bootable flash drives without fear of any devastating consequences.
How UEFI Works
UEFI boots strictly in accordance with the established rules. If the OS does not support UEFI, BIOS emulation mode is activated. The process of booting a BIOS-based PC is quite simple: after pressing the power button, the BIOS starts, which checks the status of the hardware and loads the firmware - simple drivers for individual hardware components. The BIOS then searches for the OS bootloader and activates it. That, in turn, loads the operating system or displays a list of available operating systems.
UEFI-based computers boot in the same way, only until the boot options are searched. After that, everything is different. UEFI has its own OS bootloader with integrated startup managers for installed systems. For it, a small partition (100-250 MB) is created on the disk, formatted in the FAT32 file system, called the Extensible Firmware Interface System Partition (ESP). It contains drivers for hardware components that can be accessed by the running operating system. The general rule is that, with the exception of DVD, UEFI can only boot from media formatted with the FAT32 file system.
UEFI is a complex mechanism
ESP has its advantages: thanks to UEFI drivers and an OS loader, Windows starts up faster and more adequately responds to critical driver errors. But the UEFI interface also imposes restrictions: it allows you to install the OS only on hard drives that are marked according to the GPT standard. The latter is not supported by any BIOS version, since, unlike the traditional markup scheme (MBR), it uses 64-bit sector addresses. In addition to Windows 8, only 64-bit versions of Windows Vista and 7, as well as Linux with kernel 3.2 and higher, support the UEFI interface. Moreover, for PCs certified to work with the G8, Microsoft prescribes the use of the Secure Boot option. In this mode, UEFI only runs validated OS loaders that contain Microsoft digitally signed drivers.
Along with Windows 8, only the Shim (Linux) bootloader has drivers with the necessary signatures for Secure Boot. Other OSes don't have them. Therefore, if you want to install Windows 7 or Vista on such a computer, in addition to the G8, you need to open the UEFI menu and disable Secure Boot. If you select a non-UEFI-compatible second OS, you will need to use the Compatibility Support Module (CSM), which can be enabled in UEFI. Unfortunately, manufacturers use different versions of UEFI and it's sometimes difficult to figure out how to disable Secure Boot and enter BIOS emulation mode. We will consider these questions further.
UEFI Based PC Boot Process
Depending on the configuration, UEFI either boots the computer on its own or enters a standard BIOS emulation mode. Only then does the Windows boot manager start.
Installing Windows on a PC with UEFI and Secure Boot
On a Windows 8 PC based on UEFI Secure Boot, other versions of the OS can only be installed under certain conditions. The user must select the correct boot mode in advance and prepare the installation flash drive accordingly.
Enabling BIOS emulation mode
Complete confusion: the way to enter BIOS emulation mode depends on the UEFI version. On Sony VAIO (1) you need to activate the "Legacy" option, on ASUS Zenbook (2) - "Launch CSM".
UEFI setup
Each manufacturer uses its own version of UEFI in laptops and ultrabooks. However, it does not provide access to all the necessary functions. Often, when booting a PC or laptop, the name of the button is not displayed on the display, with which you can call up the UEFI settings menu. We suggest doing the following: in the Metro interface, go to the menu "Options | Change PC settings" on the sidebar and activate the item "General | Special download options. After restarting, the OS boot manager will appear, which will allow you to open the UEFI menu. The exception is HP's UEFI, where this option is not available. The following will help here: during boot, hold down the "Esc" key. In any case, you must first find out which button allows you to enter the UEFI menu. If you change the boot mode to CSM or Legacy BIOS to boot from a rescue flash drive, you must switch from CSM to UEFI again after the restore operation, otherwise Windows 8 will not start. But there are exceptions here too: Aptio Setup Utility on ASUS computers activates UEFI automatically in the absence of a BIOS-compatible bootable media, so simply disconnecting the USB flash drive is enough.
Disabling Secure Boot will be required if, in addition to the G8, you want to install a 64-bit version of Windows Vista or 7. Sometimes the so-called hybrid mode is supported, as in devices from HP, in which UEFI can boot from all bootable media and, if necessary, switch to BIOS mode. In the widespread version of UEFI InsydeH2O, this depends on whether the laptop manufacturer has provided the ability to disable Secure Boot or not. This feature is not available on the Acer Aspire S7 and requires switching from UEFI to BIOS mode and back to disable it.
Difficulties with recovery
With the advent of UEFI, manufacturers have changed the way they work with the OS recovery system. The "Alt+F10" keyboard shortcut that was previously used, for example, in Acer models, no longer works or is assigned to other functions. And the “F9” button loads on the new Zenbook not the ASUS Preload Wizard, but the Windows 8 recovery program with an extended boot menu.
VAIO Care recovery mode on Sony laptops can be opened from a similar menu by selecting the Control Panel | Troubleshooting | Recovery". But if you start the OS boot manager and select "Diagnostics | Restore" or "Reset to original state", the device will ask you to insert the original Windows 8 disc, which is not included in the package. On Acer models, backup is performed using a pre-installed Windows program, and restoration from a backup is carried out from an external USB drive. However, you must first go to the UEFI menu and specify such a disk as bootable.
Going to the UEFI menu from Windows
If Windows 8 Advanced Startup is enabled, by selecting Diagnostics (1) and Advanced Options (2), you can access the UEFI Firmware Settings menu (3).
Useful UEFI Features
Each laptop manufacturer uses different versions of the UEFI interface and implements it in the system in accordance with their ideas. From the table, broken down by model, you will find out where the main UEFI functions are located.
Problem Solving: Disabling Secure Boot
In some cases, Secure Boot cannot be disabled directly. In Acer Aspire S7, for example, this function is not available. But if you switch to Legacy BIOS (1) and back again (2), Secure Boot will be disabled.
Everything is possible in hybrid mode
HP's version of the UEFI interface has support for hybrid mode, in which, depending on the bootable media, one of two modes is launched - either UEFI or CSM. This disables Secure Boot automatically.
Run from a flash drive
Older flash media for emergency boot and recovery work only in BIOS mode. We will make them UEFI compatible.
USB sticks have recently been increasingly used as bootable media for restoring or installing Windows. This is due to the fact that optical drives are very rarely installed in modern laptops. If you have studied the UEFI settings on your computer, it is recommended that you upgrade your flash drives as well. With the advent of UEFI, all available bootable flash drives can no longer be used in the usual way. For example, if you created a bootable USB using UNetbootin, you will need to start your PC in CSM mode. The same applies to all old flash drives, as the developers of Linux Live distributions (for example, GParted) only in the latest, most recent versions of their applications began to add a UEFI-enabled bootloader and Secure Boot functions.
The easiest way is to disable Secure Boot in UEFI, then create a UEFI compatible flash drive using the free Rufus program, and then copy the latest version of GParted to it.
Microsoft software is outdated
Windows bootable USB media has slightly different rules. For UEFI compatibility, they must be formatted with the FAT32 file system. Many users, even for Windows 8, create bootable drives on flash drives formatted using a program from Microsoft, which is part of the "seven". However, this application formats the drive in the NTFS file system by default, as a result of which the system present on the media cannot subsequently be installed on a computer with UEFI. Instead of waiting for an updated program from Microsoft to be released, you can manually create a bootable drive. To do this, first format the USB flash drive using a free utility. Then open the ISO image in Windows 8 and copy the files it contains to the media.
But in order for a UEFI compatible flash drive with 64-bit Windows 7 to boot without any problems, you will need to copy the UEFI bootloader to the correct directory on the flash drive. To do this, using the free 7-Zip archiver, find the Install.wim archive file in the Sources folder in the ISO image that contains the Windows 7 installation files and open it. After that, copy the bootmgfw.efi file from the 1\Windows\Boot\EFI directory. Then save it to a flash drive in the efi\boot directory and rename it to bootx64.efi. After that, you can work with the USB drive in UEFI mode, and you will be able to install Windows 7 from it without any problems.
Creating bootable flash drives based on Live systems
For UEFI compatibility, flash drives must be formatted in FAT32. For example, UNetbootin (1) creates bootable drives based on Linux Live distributions by formatting them in FAT. However, the Rufus(2) utility offers a more correct option.
Flash drive for OS recovery on PC with UEFI
Flash drives based on recent Live systems, such as GParted, are able to access UEFI PCs without problems, since their built-in tools - such as GPart (1) and TestDisk (2) - can work with GPT partitions.
Formatting a bootable Windows flash drive
The 64-bit version of Windows 7 can also be installed on a PC with UEFI. If you want to perform this operation from a USB drive, you must format it using the Windows DiskPart program in the FAT32 file system and make it bootable.
Extracting the UEFI bootloader
A Windows 7 UEFI compatible flash drive additionally needs a UEFI bootloader - bootmgfw.efi. It must be manually copied from the install.wim archive to a USB flash drive using the 7-Zip program or any other archiver.
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