Sunday, 3 May 2020

How to boot 64-bit Linux ISOs on a 32-bit UEFI system (such as the Asus T100)

Some systems such as the Asus T100 Transformer notebook range are a bit of an odd fish!

They have a 64-bit CPU but because they have limited SSD storage (e.g. 32GB or 64GB), the manufacturers use a 32-bit version of Windows. This means that because Microsoft insist that OEMs ship with Secure UEFI enabled, the manufacturers have to use 32-bit UEFI firmware.

In the case of the T100, the firmware does not support Legacy\MBR mode (no CSM option) so we usually need to find UEFI32 OS's.


We can however disable Secure Boot on the T100.

Since most Linux distros are UEFI 64-bit only (there are very few UEFI32 versions), this presents a bit of a problem!

However, you can still try to boot most 64-bit Linux ISOs using E2B+agFM.

Just try the 'custom' icon if one is presented in the list (if agFM recognises the distro):

I don't have a T100, but Mehdi had just this issue and found that he could boot to Parted Magic using the custom menu entry (after disabling Secure Boot).

Since you can add a persistence file (e.g. Ubuntux64.isopersist + Ubuntux64-rw) then this is a way of being able to test out different Linux distros.

This trick won't work for Windows-based ISOs though, or Windows 64-bit VHDs or WIM files, 32-bit VHD or WIM files may work only if they contain the EFI loader file.

For example, for a Sergei Strelec ISO, extract the \SSTR folder to the root of any partition on your E2B drive (\SSTR). Then move the 32-bit .wim file to the \_ISO\WINPE folder (or any folder). Now you should be able to UEFI32-boot and select the strelec10Eng.wim file and get a fully populated WinPE Desktop. The .wim files in the \SSTR folder can be deleted or copied to \_ISO\WINPE as well for 64-bit systems.

11 comments:

  1. i have one of these tablets and now i know why e2b wont boot up on the dam thing Legacy\MBR mode , i always have to put the recovery image on a seperate usb stick then it boots ok

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  2. T100TAF & Xubuntu 20.04 x64. I'm getting this error:(initramfs) could not find the ISO

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    Replies
    1. Are you sure that is the exact wording of the error message?

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    2. There's more: https://postimg.cc/rdVqFZss

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    3. There's more: postimg.cc/rdVqFZss

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  3. Maybe Xubuntu kernel does not have NTFS driver? Try placing the ISO on the FAT32 partition.

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    Replies
    1. It boots from the NTFS partition on different devices.

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  4. I am not sure if the message is a ventoy message or a linux kernel message. The long text about booting to Windows suggests it is a ventoy message and that ventou cannot mount the ISO to map it as a 'CD'. So does a Ubuntu ISO work?

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  5. I tried Xubuntu 18.04.3 LTS x64 using UEFI64 - agFM - Ventoy ISO boot - works OK.

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  6. That was UEFI64 boot.
    I seem to remember ventoy does not support UEFI32...

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  7. More testing. It can boot fine but rarely. Like 1 in 10 tries.

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