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Questions tagged [uefi]

The Unified Extensible Firmware Interface (UEFI) is a specification that defines a software interface between an operating system and platform firmware. UEFI is meant to replace the Basic Input/Output System (BIOS) firmware interface.

The Unified Extensible Firmware Interface (UEFI) is a specification that defines a software interface between an operating system and platform firmware. UEFI is meant to replace the Basic Input/Output System (BIOS) firmware interface.

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How does UEFI work?

I was studying about bootloaders when exactly came upon the term UEFI. I can understand some things about UEFI. But still, In what mode(Real,Protected,Long) does a system with UEFI start? If normal boot loaders cant work with UEFI, Then what is the…
prog481
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Writing an OS with UEFI

I haven't been coding much lately, but I've decided I want to start working on OS development again. Recently I heard about a system better than BIOS. I want to develop an OS for a platform that uses EFI rather than BIOS. I don't know where to…
Hudson Worden
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How can I prevent MSVC from replacing my memset with its memset?

I am building an EFI driver and therefore cannot use stdlib, so no memset. I am also running after ExitBootServices, so no edk2 CopyMem. This is my function: void Set_Memory(VOID* Dest, UINTN Len, CHAR8 Val) { for (int i = 0; i < Len; ++i) …
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Install VMware : Could not open /dev/vmmon: No such file or directory. Please make sure that the kernel module `vmmon' is loaded

I downloaded the VMware S/W from official website and installed the same. When I try to run any virtual machine it shows error Could not open /dev/vmmon: No such file or directory. Please make sure that the kernel module `vmmon' is loaded and says…
Manthan
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Use of redefining void pointer to pointer to an anonymous structure?

I was working with UEFI driver-related code, and I came across this: /* EFI headers define EFI_HANDLE as a void pointer, which renders type * checking somewhat useless. Work around this bizarre sabotage * attempt by redefining EFI_HANDLE as a…
achoora
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How does the GRUB 2 UEFI loader know where to look for the configuration file (or where the 2nd stage's files are located)?

If I use GRUB 2 on a GPT-enabled partition, how does the loader "know" where to find its configuration file and other second stage's files? Note: I found some mentions about a configuration file which is located in the same folder as GRUB's EFI…
Sap
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What sort of things are UEFI "applications" actually used for?

I'm interested in PC firmware programming, and am just studying the UEFI spec. To my surprise, it seems like a spec for an entire OS which is embedded in firmware. You can even write UEFI "applications", which run directly using the UEFI boot…
Alex D
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How does UEFI boot mode boot flows?

The expression of this question is same as What is UEFI's boot sequence?, but it doesn't seem what I want. I'd like to know UEFI sequence in instruction perspective. For example, in case of BIOS boot mode, in simplified fashion, Computer power is…
YoonSeok OH
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Debug GRUB2 EFI image running on QEMU

What I want to achieve I want to customize a GRUB EFI image, and debug it while running on QEMU. So I'm trying to debug a vanilla GRUB image before customizing it. What I have done so far I downloaded GRUB2 from http://git.savannah.gnu.org and…
lseki
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How does processor read BIOS from SPI flash?

A typical x86 systems has firmware (aka BIOS or UEFI) stored in a SPI based Flash chip. When the power-on happens, the processor starts executing at Reset Vector which is pointing to memory-mapped SPI chip where BIOS is stored. From here onwards,…
Naveen
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Run a UEFI shell command from inside UEFI application

I'm new to UEFI application development. My requirement is that, I need to run an UEFI shell command from my UEFI application (app.efi) source code. Need guidance on how I can do this. Example, cp command in UEFI shell is used to copy a file from…
Keshava GN
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Are Intel's PTT and TPM equivalent

Are Intel PTT (Intel Platform Trust Technology) and TPM chips functionally equivalent? If I had a board with a Intel processor that supported PTT, would I have the same functions as if I had a hardwired TPM chip, e.g support of Trousers, etc.? How…
user2881914
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Stuck on EFI shell while trying to run macOS Catalina 10.15 on virtualbox

I have been trying to install macOS Catalina on virtual box foloowing this tutorial: https://techsprobe.com/install-macos-catalina-virtualbox-windows/ When getting to the step of having to actually install catalina the virtual machine boots into an…
Holmes
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Windows equivalent to efibootmgr?

Windows keeps overriding the UEFI boot order even if I change it with efibootmgr from Ubuntu. However BootNext option is not overridden, that is, I can set BootNext to Ubuntu and it boots into Ubuntu upon rebooting. I, therefore wrote the following…
Naveen Unnikrishnan
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The realisticity of writing a full operating system as an UEFI application

Technically UEFI provides a lot of functionality which is part of the groundwork of an operating system, such as a file system. In a way, it is a shame that everything gets discarded and reimplemented by the operating system in the process of…
Thomas F.
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