Precision 7520 (6th Gen Intel) and Windows 7 32-bit

Just FYI in case anyone tries it (or wants to), Windows 7 is supported on the Precision 7520 (and similar era) with 6th Gen Intel CPU but only 64-bit flavor of Windows 7, not 32-bit (a.k.a x86). I tried it out of curiosity but also because I have some potential legacy needs that I wanted to know if I could use this model for.

Not only are 32-bit drivers not available for some devices (touchpad, track button, Qualcomm wired ethernet), but the BIOS/firmware is reserving a big chunk of <4GB memory address space to hardware, that become unavailable to the OS. e.g. I have 8GB RAM installed, which of course is not all available to Windows 32-bit client OS anyway. But typically, there should be about 2.9 ~ 3.2 GB useable exposed to 32-bit OS, after hardware reserved. But I'm only getting 1.7GB useable and nothing can change it.

Linux 32-bit versions that support more than 4GB via PAE kernel is an option but I have not tested it and even Linus Torvalds has said PAE is really a terrible solution. I think I remember reading it was so problematic that some 32-bit Linux distros ceased to support PAE for >4GB, same as Microsoft decided except on enterprise segment OS.