Windows – Install Grub2 (with EFI-IA32 support) to the ESP partition from within Windows 8.1 (32-bit) – Bay Trail tablet

32-bit64-bitgrubuefiwindows 8.1

This is a very complicated idea, and it's been stuck in my head for a while now, so bear with me.

In this question, when I say "Grub2", I am referring to the "EFI-IA32 version". The device I will be using contains a 32-bit UEFI BIOS, but has a 64-bit CPU.

I want a folder/archive that I can download, that contains a pre-compiled Grub2 and all of its configuration files (preferably the latest version).

I do NOT want 'Grub4DOS' 'SuperGrub2' or anything like that, I want the same Grub2 that is installed alongside Ubuntu 15.04, 14.10, ect…

I want to be able to COPY this Grub2 folder into my ESP partition, and then use my 32-bit UEFI BIOS to enter Grub2, and boot an OS.

And before you start telling me it's "impossible becase 32 and 64 bit don't work together", I know for a fact it will work, because I have done it before with a 64-bit Ubuntu 14.10 on a 32-bit UEFI.

I understand that I could just install ubuntu instead of going through all this, but I'm specifically trying to avoid installing a seperate OS just to get a tiny bootloader onto my ESP.

in case you still don't understand, GRand Unified Bootloader, version 2 (EFI-IA32 version), here's the link to the Ubuntu package that I want to be used to make the pre-compiled folder (source is listed here as well).

Any answers that have anything to do with "you can't run a 64-bit OS on 32-bit" or "What's the point" will be flagged as off-topic, you have been warned.

Best Answer

Found it!

I downloaded the newest Ubuntu (15.04, 64-bit) ISO file, I extracted the /boot and the /EFI folders from the root of the ISO. I copied the folders to my ESP partition, and edited the grub.cfg file as needed (in EFI/boot/), and copied the bootIA32.efi file to the EFI/boot folder.

I now have a fully working 64-bit Grub2 on a 32-bit UEFI BIOS self-contained in the ESP!

Now, if anyone would care to take a look at my other question about Grub2, that would be fantastical.

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Windows – Grub rescue command line, chainloading Windows 7 installer

Just have been there too (where you are right now) And if you tablet is a Toshiba 10"... we are brothers in arms... ;-)

Just add this entry to your GRUB2 menu

menuentry "Windows 7" {
     insmod part_msdos
     insmod ntldr
     insmod ntfs
     ntldr (hd0,msdos1)/bootmgr
}

UEFI Mode – Install Windows 8.1/10 32-bit in UEFI Mode

An EFI can run programs, including boot loaders, only for the same architecture for which the EFI is compiled. On an x86-64/AMD64/X64 system, this means that if the EFI is 64-bit in nature, it can launch only 64-bit boot loaders, and if the EFI is 32-bit in nature, it can launch only 32-bit boot loaders. The Windows boot loader, in turn, can launch only a like-bit-depth kernel (AFAIK), and so on down the chain. Thus, if you have a 64-bit EFI, you can launch only a 64-bit Windows, AFAIK.

In theory, you could work around this limitation with an appropriate boot loader. GRUB can launch a Linux kernel across the bit-depth boundaries, for instance. So can Apple's macOS boot loader (to launch a 32-bit kernel on a 64-bit EFI; I don't think it works the other way around). In practice, AFAIK this isn't possible with Windows.

By enabling the Compatibility Support Module (CSM), you can boot either a 32-bit or 64-bit OS, but only in BIOS/CSM/legacy mode. This has some drawbacks, as outlined in my answer to this question (referenced earlier in athosbr99's comment). If you want to install your 32-bit Windows on the computer's only hard disk, you'd pretty much have to go all-in on this. (There are ways to mix boot modes on a single disk, but there are so many caveats that I don't want to confuse the issue by describing them.) If you wanted to dual-boot with another OS, particularly on another disk (say, 64-bit Windows internally and 32-bit Windows on an external disk), you could install the 64-bit OS(es) in EFI mode and the 32-bit OS(es) in BIOS mode, then use the computer's built-in boot manager or my rEFInd boot manager to manage the boot process. This would be a bit of a pain to set up, though, and you should research the issues thoroughly before attempting such a cross-mode install. Start with this page of mine, which describes the CSM and its pitfalls. (It's written for Linux users attempting a dual-boot with Windows, but the background information is relevant.) I then recommend reading the rEFInd documentation thoroughly, and paying careful attention to the description of the scanfor option in refind.conf.

Overall, then, your best bet is to either stick with a 64-bit boot in EFI mode or wipe everything, turn on the CSM and install the 32-bit Windows in BIOS mode. I don't know if Windows' 32- vs. 64-bit performance is sufficiently different on a system with 2 GiB of RAM to justify the switch. Note that most manufacturers install a bunch of bloatware, and eliminating that is likely to improve performance quite a bit, so you might want to look into that before installing a 32-bit Windows.

Best Answer

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Windows – Grub rescue command line, chainloading Windows 7 installer

UEFI Mode – Install Windows 8.1/10 32-bit in UEFI Mode

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