PXE Booting 5.2.1-RC2 on Thinkpad X31

[John Morgan Salomon]

Hi there,

I've got 4.9-RELEASE running on my Thinkpad, and am trying to netboot
5.2.1-RC2.

The laptop has no floppy or cdrom;  I'd previously managed to install
a pre-release 5.2 on a separate hard drive, but it's pretty unstable,
doesn't like ACPI, has trouble finding devices, hence the 5.2.1-RC2.

I've been trying various combinations of tftpboot and nfs to get 5.2 
booting on the thing--I have finally gotten the laptop to boot the
contents of the 5.2.1-RC2 kernel and mfsroot floppies, and gotten
to a setup screen:

-> pxeboot
include /pxeroot/boot/device.hints
load /pxeroot/kernel
/lad -t mfs_root /pxeroot/mfsroot

However, no matter what I do, the machine inevitably freezes after a few
seconds.  There's no error messages, I can't get an emergency shell open,
nothing.

Can anyone give me some hints as to what I might be doing wrong?  Has anyone
gotten 5.x running nicely on a Thinkpad X31?  Any ideas would be appreciated.

Cheers,

-John