Win10PESE with Bios +UEFI

Forgive me if this has been answered but I haven't tried to get this to work in a long time and I'm not sure I found a solution when I was trying to get it to work. Has anyone been successful in getting a Win8.1pese or 10pese to boot while also offering to boot to a grub2 or grub4dos menu yet? The problem I have is on a secure boot system my PE boots fine but it bypasses the grub options I've added, like bootable imaging apps and some other images for diagnostics. I'm just struggling to understand the language in order to get my project completed. Back when I was using ezboot(before UEFI and secure boot garbage) I had no issues getting anything to work but I am at a loss here.
Goal- Win10pese to boot via uefi or bios but also have the option during boot to jump to my grub menu to load other images. I've downloaded UEFI-Multi but don't completely understand what the process entails to get it done correctly for my purposes because it seems the documentation only deals with parted magic and a win8 pe and not a thorough list of options like Ive seen here and in the past reboot.pro before you guys moved here.

Any assistance appreciated.

Sorry little tired and have had a few to drink. My son started kindergarten today among other things we are dealing with so a bit on the stressed side lol.

Cheers,

Goodwin

The problem I have is on a secure boot system my PE boots fine but it bypasses the grub options I've added, like bootable imaging apps and some other images for diagnostics.

Hi

It looks like you are installing/using Grub2 in legacy mode (installed to MBR). UEFI works differently and never executes any code written on sector 0 aka MBR of a hard drive.

Legacy BIOS boot process >

1. Complete power on self test (POST).

2. Check the boot order and if HDD is listed as first, check for MBR magic number AA55 on LBA 0 (first logical sector).

3. If MBR magic number is present, execute the assembly language instructions written on the MBR. This code will be different for each boot loader/boot manager. For example, Windows NT5 compatible MBR code will look for a partition marked as Active and if one found, execute the code written on VBR (Volume Boot Record) of the partition. This VBR code will then look for and load ntldr (NT loader) and it's the responsibility of the ntldr to proceed with OS loading process. Grub4dos MBR code will usually search for and load "grldr".

UEFI BIOS boot process>

UEFI BIOS is written in high level languages like "C" (instead of Assembly) and has much more capabilities like reading a file system directly (ie FAT16/32 and/or NTFS in some cases). This allows the UEFI firmware to directly read and load the OS boot loader without the need to read and execute any RAW assembly code written on LBA 0 of the disk.

Here is how the general UEFI boot process works :

1. Complete the POST process.

2. Identify the "EFI System Partition" via checking the GUID (in case of GPT style partitioning).

3.Directly read the file system and check for the presence of \EFI\BOOT\BOOTX64.EFI file (UEFI x64 boot loader ) and chain-load it.BOOTX64.EFI proceed with loading the respective OS (Windows/Linux) .If the firmware is capable of "SecureBoot" and if it's enabled, the boot loader should be a signed one. This will make sure that the boot process is free from any boot viruses.

Hope that now you will have a basic idea of how a UEFI boot process is different from legacy/mbr BIOS mode. Since the UEFI boot process completely ignores the MBR, executing grub4dos or Grub2 legacy code is not possible. If the UEFI firmware supports legacy/CSM mode, you can enable it to boot from a grub4dos based bootable USB stick.

Grub2 has a UEFI version and one can actually create a multi-boot USB stick using it. However you need UEFI based bootable images and the Grub2 menu should be manually edited to chain-load the respective UEFI boot loader of each utilities. That's certainly not an easy task.

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- After bootx64.efi loads, what happens, and which of the other files are needed (specifically for USB boot only?) Let's use an enUS standard ADK PE as an example:

"bootx64.efi" and Bootmgr both will usually try to read and populate BCD and load the "Windows\system32\winload.exe" (or Winload.efi) file of the default Windows boot entry. Winload.exe or Winload.efi then load the ntoskrnl.exe (NT Kernel) which will take command of the boot process and OS initialization.

bootmgr.efi (why is this there, when UEFI is looking in EFI\Boot ?)

"bootmgr.efi" is certainly not needed for booting from USB/HDD. I have read that it may be needed for CD/DVD booting but unable to verify it since i stopped using optical discs. May be later experiment with virtual machines.

"UEFI\Boot" is the default location the firmware will look for the boot loader file (bootx64.efi or bootx86.efi) if the boot mode is set to UEFI (and not CSM). The path and names are standardized by "UEFI consortium" - http://www.uefi.org/. But it may be possible to alter the default path and name by altering UEFI NVRAM data. More details can be found at  http://www.rodsbooks.com/efi-bootloaders/installation.html

EFI\Boot\en-us\bootx64.efi.mui (is this optional, or only needed when using a different language?)

Certainly optional at least for en-US version. UEFI seems to boot and display boot menu without the mui file but i am not sure about other languages.

EFI\Microsoft\Boot\Fonts\malgun_boot.ttf (and other fonts, are they optional/ when are they used?)

As far as i know, the fonts are for foreign languages.

EFI\Microsoft\Boot\BCD (why is it in de \Microsoft folder, not in plain \EFI folder?)

EFI\Microsoft\Boot\Resources\bootres.dll (another confusing file, what does it do and why does it seem to be optional)?

I don't know either the exact reasons why they choose to use "EFI\Microsoft" folder. My best guess is to keep the "EFI\boot" folder clean and simple. Linux distros like "Ubuntu" also follows the same convention. In an Ubuntu CD, you will only find "BOOTx64.efi" and "grubx64.efi" files inside the "efi\boot" folder. However grub2 resources are located at "\boot\grub" folder (grub2 won't boot without them).

bootres.dll traditionally contains a compressed animation of Windows boot time logo. If you open the dll with resource hacker, you will find the boot time logo data under "RCData" section. Right click on the "1:1033" resource and select "Save Resource to a bin" option. You can open the saved file using 7-zip and view the boot logo screen bmp files inside it.   

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Hi

Honestly, i have no clue about the difference between the two flavors of bootmgr. The Acronis issue  sounds like a driver signing problem indeed. Easiest way of course is to replace the standard BCD with the modified one from SE.

Btw, the below links contain some useful info about the boot process.


https://neosmart.net/wiki/mbr-boot-process/

https://technet.microsoft.com/en-us/library/bb457123.aspx
 

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I will have to cross that bridge when I have UEFI hardware to test, it could even be an ASUS-specific thing, who knows...

Easiest way to test UEFI booting without hardware is to use "Hyper-V" (which is available with 8.1/10 Pro). It even supports SecureBoot - make sure to select the "Generation 2" virtual machine.

Considering that "Acronis" drivers are usually signed by an authorized CA, the error might be something else than the "signature" issue.

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Hi all,

I know that someone created a good tool using Grub2 to multiboot WinPE, Linux, Antivirus... iso files.
You can search with phrase "AIO Boot - Grub2/Grub4dos/Syslinux/Clover/rEFInd, UEFI-GPT/Legacy-MBR, USB/HDD/DVD, LAN (PXE)". However, this tool was written in Vietnamese, so you can use Google Translation to translate into English.

Hope that you can enjoy the tool.

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Good luck with your UEFI experiments  .