It's not clear why you want to do this, let me makes some guesses.
If you have 32 bit hardware that won't support 64 bit, then the bios may also not support UEFI, or it may have UEFI support that is old enough to be buggy. It might boot with ipxe, and I've gotten that to work, but when I was using that, I had to support 3 different methods of loading the live disk due to the variety of bugs in 32 bit UEFI firmware. Additionally, the easiest way to pxe boot with ipxe is to just load the whole image into ram, and 32 bit hardware typically doesn't have enough ram to do that. It's much easier to just boot from USB or CDROM.
As to what live image you can use, Ubuntu 18.04 supports 32 bit, although it drops drivers for some 32 bit hardware, so you might need Ubuntu 16.04. Older versions of CentOS support 32 bit as well, but I'm not sure if you need CentOS 6 or 5 without doing some research. (Added note suggested by comments: a rescue disk is more likely to have a current 32 bit version, and also likely smaller, which would make loading to ram easier.)
If you are trying to install a 32 bit image on 64 bit hardware, my suggestion is dont -- although this is still much easier than on 32 bit hardware. Presumably you are doing this to run a 32 bit binary. Here are alternatives:
- Load the 32 bit compatibility libraries into your 64 bit linux. It
should run the binaries just fine once you've satisfied all the library dependencies.
- Build a container using an older version of linux that suports 32 bit. Any container engine should work, including Docker or Apptainer, etc.
- Use a VM emulator like vmware or qemu and run an older OS inside the VM.
If you have to use an older OS, running a container or VM is preferable to running on bare metal, as you can use the host to firewall the older OS and bugs in the (presumably unpatched) older OS you have to use won't be as much of an issue. Also, you'll get full use of your 64 bit hardware where a bare metal 32 bit OS would not work nearly as well on the newer hardware.
