UEFI vs Legacy Mode: TPM Device (English)

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Laptop Technicians,

Do you know what are the differences in the boot modes of your laptop and what difference do they make to your work? Let us understand this complex but very important topic in simple language today. By reading this article, you will not only increase your knowledge but will also be able to provide better service to your customers.

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UEFI and Legacy Mode: Introduction

UEFI (Unified Extensible Firmware Interface) and Legacy Mode are two different ways your computer boots.

1. Difference between UEFI and Legacy mode

   1. UEFI (Unified Extensible Firmware Interface):

   • Modern Firmware Interface: UEFI is a modern firmware interface designed to replace the older BIOS (Basic Input/Output System).
   • Graphical User Interface: UEFI provides a Graphical User Interface (GUI) which makes the user interface more user-friendly.
   • Disk Support: UEFI supports hard drives larger than 2.2TB, while BIOS was limited to this.
   • Fast Boot: UEFI provides faster booting time.
   • Secure Boot: UEFI has a Secure Boot feature that protects the system from modified bootloaders without permission.
   • Network booting: UEFI better supports booting from the network.

   1. Legacy Mode(BIOS):

      • Old Firmware Interface: BIOS is an old firmware interface that acts as an intermediate between the computer's hardware and the operating system.
      • Complex Interface: BIOS does not have a graphical interface, but rather it is a text-based interface.
      • Limited disk support: BIOS does not support hard drives larger than 2.2TB.
      • Slow Booting: BIOS has a longer booting time.
      • Security Features: BIOS does not have a secure boot feature.

The way to work

1. UEFI:

   • When the computer turns on, UEFI runs first and initializes the system hardware.
   • UEFI boots the operating system through a bootloader.
   • During UEFI booting, an interface is created between the hardware and firmware that allows the operating system to access the hardware.

2. Legacy BIOS:

   • When the computer is turned on, the BIOS runs first and performs a POST (Power-On Self Test).
   • The BIOS initializes the hardware and loads the bootloader from the boot device.
   • The BIOS loads the operating system through the boot sector (MBR).

Difference

• Compatibility: Legacy BIOS provides better compatibility with older hardware and operating systems, while UEFI with modern hardware and operating systems.
• Speed: UEFI provides faster booting time.
• Security: UEFI has more security features such as Secure Boot.
• Storage: UEFI supports drives larger than 2.2TB, while BIOS was limited to this.

After understanding both these modes, you can choose the right mode as per your system and requirements. 

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Operating system support

• UEFI: Windows 8 and above, some Linux distributions, and macOS
• Legacy Mode: Windows 7 and earlier, older Linux distributions

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TPM (Trusted Platform Module) is a hardware-based security module that plays a vital role in the security of a computer system. The main functions of TPM and its role in UEFI/Legacy mode are as follows:

Role of TPM

1. Cryptographic Operations:

   • Managing keys: The TPM securely stores and manages cryptographic keys. These keys are used for data encryption, decryption, and signature generation.
   • Random number generation : The TPM generates secure random numbers, which are important for cryptographic operations.

2. System Integrity:

   • Boot process security: TPM verifies the integrity of the system during the boot process. It ensures that no unauthorized changes are made to the bootloader and operating system.
   • Root of Trust: TPM provides a 'root of trust', which guarantees the security of the system's booting and operation.

3. Secure Boot and Measurement:

   • UEFI Secure Boot: TPM and UEFI together enable the secure boot process, allowing only trusted software to boot the system.
   • Measurement storage: The TPM stores important measurements during the system's boot process and uses them to verify.

Role of TPM in UEFI

• Secure Boot: UEFI and TPM work together to support the secure boot process. The UEFI secure boot feature is supported by TPM, which prevents unauthorized and malicious code from booting.
• Platform Configuration Registration: The TPM stores and verifies the Platform Configuration Registration during the UEFI boot process.

Role of TPM in Legacy Mode

• System Integrity: While Legacy BIOS doesn't feature Secure Boot, the TPM can still check the system's integrity during the boot process.
• Data Encryption: TPM is used for data encryption and decryption, which may be important even in Legacy mode.

Difference

• Secure Boot: TPM with UEFI supports Secure Boot, which is not possible in Legacy BIOS.
• Advanced security features: UEFI and TPM together provide more advanced security features, such as Secure Boot and Platform Integrity Measurement.

TPM is used to strengthen the security of computer systems, and it specifically works together with UEFI to secure the boot process and system integrity.

TPM ERROR may occur after programming the BIOS because the BIOS settings are reset and the TPM needs to be setup again. Because:

1. TPM settings may have been reset.
2. The synchronization between the BIOS and TPM may be disrupted.

Solution :

• Reconfigure the TPM settings in BIOS.
• use downgrade bios file 
• Reset the TPM and update the BIOS again.

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Summary and motivation

Laptop repairing is not an easy task, but with the right knowledge and tools, you can solve any problem. Knowing about UEFI and Legacy Mode will not only simplify your work but also make you an efficient and competent technician.

If you have learned something new by reading this blog, please follow my blog and share this information with your friends. Your suggestions and feedback are always welcome.

Thanks to all you technicians for reading this blog. With your hard work and dedication you are not only fixing laptops but also solving people's problems. Keep working hard in the same way and keep exchanging knowledge by following my blog.

Thanks!  -Harshad Patel