[syslinux] is substitution possible?

[Wagner Ferenc]

"H. Peter Anvin" <hpa at zytor.com> writes:

> Wagner Ferenc wrote:
>
>> [...] But why do you mention the TFTP server?  It just serves the
>> config file to PXELINUX, which could munge it to its liking,
>> couldn't it?
>
> One way that has been discussed in the past is to do an HTTP to TFTP
> proxy server, another variant to execute from a program.
>
> The big problem with all of this is that it has to be done quickly,
> because in the TFTP protocol there is no way to distinguish a request
> retry from a second request, which could flood the server very quickly
> if substitution is slow.  In order to support the "tsize" option,
> which PXELINUX requires, one has to have the total transfer size ready
> before transfer can begin.

To be honest, I barely understand a word, but I feel like we're
talking about different things...

First of all, I don't know the details of PXE.  What sort of
information does pxelinux have access to?  Can it see the DHCP lease?
According to the FAQ, some options can be passed in.  But I wouldn't
like to change the configuration file name based on the lease, but
just do some simple text substitution.  So: pxelinux gets its config
file by TFTP as usual.  Then, wherever it sees $NAME, substitutes the
host name found in the lease into its place.  Or runs it through the
Perl script presented as some obscure DHCP option, pardon me. :)
Then it parses the preprocessed config file and goes on.

Maybe I don't see something obvious, but it doesn't seem connected to
the TFTP protocol or its tsize option...
-- 
Feri.