[syslinux] Best way to deal with an idiosyncracy of Intel Boot Agent (IBA)...

Jeffrey Hutzelman jhutz at cmu.edu
Mon Mar 17 22:51:53 PDT 2014

On Tue, 2014-03-18 at 00:02 -0500, Spike White wrote:

> So if I specify Bootfile name (option 67), frequently that's the last real
> DHCP option.  Thus the next byte is the DHCP "end option" aka 255. The IBA
> code mistakenly parses this as "/boot/efi.x64/syslinux.efi^X",  where ^X
>  is a char with value 0xFF (255).  It requests this filename from the TFTP
> server, which (of course) has no file by that name.

We noticed this back in 2002, when we were still using our own TFTP
server.  My solution at the time was to simply have the TFTP server drop
a trailing 0xff from any filename.  Today, we use the following mapping

rg    (.*)ÿ$                                 \1

Another possibility, if you have some control over options generation,
is to immediately follow the filename option with a NOOP, which is tag 0
and has no length.  This is not included in the option length, but I
expect the broken PXE stack will do the expected thing.

-- Jeff

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