[syslinux] Multicast TFTP

[H. Peter Anvin]

Hello all,

As several of you have asked, tftp-hpa isn't likely to support multicast
TFTP any time soon, because such support would require some very
fundamental structural changes which would be very much against the goal
of keeping tftp-hpa "psycho portable", as I like to say.

However, I'm playing with the possibility of supporting multicast TFTP
(the RFC version, not the weird "MTFTP" Intel/PXE version) in PXELINUX.  I
originally thought it was impossible without completely breaking the very
nice filesystem abstraction model I had already implemented, but I think I
might be able to deal with that, at least for the large files (kernel and
initrd, as opposed to config and display files.)

However, in order to test this I need a TFTP server which can do TFTP
multicast.  Anyone happens to know of one?

For those of you that are interested, the reason this is tricky is that
one of the consequences of using TFTP multicast is that packets arrive out
of order.  The current SYSLINUX framework assumes sequential access.  To
make matters worse, the kernel file is not only not contiguous in memory,
you don't know what the memory layout will be until you have read the
first block.  This can be dealt with by doing large copies, of course, but
that's rather unpleasant.  It may very well be the only sane way to deal
with it, however.

    -hpa