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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.

For more information see:

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Can I write on my local filesystem using EFI

I am working on this project to write files to local filesystem as soon as the OS starts through an EFI application. I need to know if it is possible. And if yes then kindly guide me a little. Thanks
Asak
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UEFI runtime service next to OS

I had the idea of running a small service next to the OS but I'm not sure if it is possible. I tried to figure it out by reading some docs but didn't get far, so here comes my question. I read about the UEFI runtime services. Would it be possible to…
maufl
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Can a UEFI machine use BIOS interrupts?

When the kernel been loaded into the memory, can it still can use BIOS interrupts? Such as mov AX,0E820h int 15h or something.
KME
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How does LinuxBoot differs from Coreboot in the firmware phase?

I am literally confused about the use case of using LinuxBoot as the payload for Coreboot. I learned that LinuxBoot can completely replace the UEFI's DXE and BDS phases, and then can load the bootloader (say GRUB) or even the Linux kernel…
Naveen
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How to open a file by it's full path in UEFI

I'm a beginner in UEFI. I'm trying to open a file from my UEFI application. The path of file is fs1:/myfolder/myfile.txt The code (With the help of this answer) : efiStatus = bs->LocateHandleBuffer(ByProtocol, …
Keshava GN
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Who executes POST? BIOS microcontroller or CPU?

What piece of hardware executes firmware during POST? BIOS microcontroller or CPU? BIOS microcontroller is executing the firmware on ROM which has some configuration on CMOS (like a RAM). But during POST who is executing the firmware that is…
int3
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Why do we need AML - ACPI Machine Language?

As I understand, ACPI defines a generic hardware programming model where operating system relies on the OEM firmware provided AML (ACPI machine language) code to manipulate the hardware. In order to execute the AML code, operating system has to…
smwikipedia
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Modifying the ia32 feature control register on Asus Z170 board with buggy BIOS

I'm in the unlucky situation that I need to use a CPU feature that the BIOS hasn't enabled in the ia32 feature control MSR register. The BIOS does set the lock bit so I can't set the bit myself. The BIOS (Asus UEFI BIOS) has no option to change the…
Morty
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No FS0 in EFI Shell

I want to try programming for EFI so I created a VM using virtualbox, checked "enable efi" option and left CD empty. The efi shell boots how it should but instead of FS0 i only see BLK0, BLK1 etc. Is there any way to have FS without inserting USB…
Corson
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Create a Thread in UEFI

Is there a way to have a threaded application running on UEFI? I've only found a few mentions of threading in the UEFI specifications, but they didn't really answer my question.
Jeroen
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Running an EFI application automatically on boot

I can build and manually execute an EFI application in a UEFI environment. But, I'd like to have my application executed automatically at boot time. Is there a way to tell the bootloader to do this or do I need to turn my application in to a driver…
PaulH
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How to enable ACPI (for powering off) on LattePanda

I wrote this code to use ACPI for powering off computers from my program launched from 64-bit UEFI. (sorry for long code, but I think all parts are necessary) #include #define in8(data, port) __asm__ __volatile__ \ ("xor %%eax,…
MikeCAT
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Build edk2 in linux

i'm getting started to write a little and simple application with edk2. So to write a simple edk2 UEFI application , i have started like this : #git clone https://github.com/tianocore/edk2.git #. edksetup.sh BaseTools Loading previous configuration…
Esaïe Njongssi
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UEFI boot services CreateEvent() returning status EFI_INVALID_PARAMETER

I'm writing a simple UEFI application in NASM assembly, and I'm trying to make an event for a free-running timer, but the call to CreateEvent always returns EFI_INVALID_PARAMETER and I'm not sure why. section .text _start: mov [ptrSystemTable],…
Peter Frost
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How does a PCIe device appear bootable to the BIOS/UEFI?

I have an Intel based host system with a PCIe daughter card that my company has designed. We are able to have it be enumerated to allow memory to be shared with the intel processor. I am looking to make the daughter card memory space, accessible…
penguin4hire
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