T430 - won't boot with expresscard eGPU

[ianyp]

I have a T430 with 16GB of RAM (2x 8GB) non dGPU. EXP GDC Beast is the eGPU and the GPU is a 980 TI (6GB)

If I have the expresscard and GPU in it won't boot past the splash screen.

If I plug it in afterwards the operating systems (W10 or Arch Linux) complain that either there's not enough memory for the device or that the memory region assigned is invalid.

I tried doing something called the dsdt fix for windows but ended up with a BSOD. In linux the kernel parameter pci=nocrs doesn't seem to have any effect. So I'm hoping for a hardware fix.

Is this an issue with TOLUD? I have searched in vain for an explanation of TOLUD but can't find one. What is it? Some people report success with lowering it but I don't understand why that would work?

Is this different as the BIOS having 64bits of addressable memory? I asked someone on a BIOS forum and they said that the 16GB - eGPU fix wasn't relevent for this laptop. Can I work around this by flashing coreboot?

[Screamer]

If I have the expresscard and GPU in it won't boot past the splash screen.

UEFI splash screen, I assume?

If I plug it in afterwards the operating systems (W10 or Arch Linux) complain that either there's not enough memory for the device or that the memory region assigned is invalid.

This is a sign of an extremely high TOLUD value. You need to reduce it, normally with the help of an option in the UEFI. Unfortunately, most notebooks do not have such an option provided in their UEFI.

I tried doing something called the dsdt fix for windows but ended up with a BSOD. In linux the kernel parameter pci=nocrs doesn't seem to have any effect. So I'm hoping for a hardware fix.

There is no hardware fix for a problem that lies completely in software.

Is this an issue with TOLUD? I have searched in vain for an explanation of TOLUD but can't find one. What is it? Some people report success with lowering it but I don't understand why that would work?

Yes.

I suggest reading this post that was written by a user who has deleted his/her account. He/she answered a similar issue, and has more information regarding this subject.

Can I work around this by flashing coreboot?

Does coreboot have the ability to modify the TOLUD register? If the answer is a no, then it will not allow you to work-around this problem.