localboot.lua

A Lua script for syslinux' lua.c32 comboot module that uses DMI data to decide between localboot / chainloading.

Introduction

We use PXELINUX in our product to show a boot menu on client computers, with options like "Boot from local hard disk", "Install Windows", etc. Unfortunately, a lot of computers seem to have broken BIOSes and won't boot with the LOCALBOOT command, and need to be booted with chain.c32 instead. We also have encountered some computers where it works only the other way - chainloading does not work, while LOCALBOOT works fine.

To solve this issue, we have written this Lua script that uses the DMI data of the computer to decide whether it should be booted with LOCALBOOT or chain.c32. The scripts defaults to LOCALBOOT, but has a list of exceptions for computers that require chainloading.

Syslinux compatibility

Tested with PXELINUX 4.05 and PXELINUX 6.03.

Setup

Copy localboot.lua to your tftpboot folder.
Edit your pxelinux.cfg, and change the existing LOCALBOOT command to the following:
```
  kernel lua.c32
  append localboot.lua
```

debug.lua

You can optionally use the provided debug.lua script to collect the necessary data for new exceptions. It will print the most relevant DMI data:

When one of your users encounters a computer that won't boot, you can instruct them to boot debug.lua and send you a photo of the output.

Add an exception

To add the exception to the script, duplicate one of the elseif blocks and modify the string matches and the descriptive comment. Note that string matches are case sensitive and have to be exact. Look out for trailing spaces too - some manufacturers use fixed string lengths and pad their strings with spaces, e.g. "Acer ". If you're copying the data from a debug.lua screenshot, be sure to count these spaces carefully.

Usually what you want to match is either system.manufacturer and system.product_name for OEM computers:

sm == "Acer" and sp == "Aspire 3750"

Or base_board.manufacturer and base_board.product_name for custom built computers:

bm == "Gigabyte Technology Co., Ltd." and bp == "B75M-D3H"

After you have confirmed that the exception works, please consider to file a bug or to send a pull request so that everyone benefits of your improvement.

adlerweb / localboot.lua