[mythtv-users] Questions on PXE booting a frontend

[Paul Bender]

Jim Stichnoth wrote:
> I have a Zotac IONITX frontend that I'm interested in making
> completely diskless and PXE booting, and I have a bunch of questions.
> Currently it boots off a 4GB USB flash drive.  It is running MythDora
> 10.21, using the kernel 2.6.27.9-159.fc10.i686.  I have rsync'd the
> root file system to the backend machine, and that directory is
> NFS-exported.  I understand that I will need to set up dhcp, tftp, and
> syslinux (i.e. pxelinux.0) on the server.

Why are you interested in network booting your frontend? Being the 
maintainer of MiniMyth as well as someone who network boots his MythTV 
frontends, I believe I have no prejudice against network booting MythTV 
frontends. However, while network booting has both advantages and 
disadvantages. Therefore, understanding your motivation for network 
booting would help with figuring out what combination of local and 
network software would be most appropriate.

> 1. Should I expect to have to recompile the kernel to allow an NFS
> root file system?  What config options should I look for?

As Jarod already mentioned, as long as you create an initrd with the NFS 
root file system driver, the TCP/IP driver and the hardware's Ethernet 
driver, then you do not need to recompile the kernel.

> 2. Can the DHCP service in a home router and a Linux DHCP/PXE server
> coexist on the same network?  I would prefer the home router to handle
> most DHCP requests and the Linux server to handle just the PXE-related
> requests for this frontend, so that e.g. my wife doesn't lose DHCP for
> her laptop computer when the Linux server is down.

In general, I do not believe that it is worth trying to run separate 
BOOTP and DHCP servers on the network. At best, it is a challenge to 
configure. At worst, the DHCP server does not support it.

If you need to use an existing DHCP server, then you might consider 
booting using gPXE on a USB driver. You can hard wire it with the server 
(TFTP or HTTP) rather than depending on the BOOTP/DHCP server to provide 
it. However, it requires you compile gPXE in order to embed the server 
address in the gPXE binary. Again, whether or not this is the right 
solution depends on the reason for network booting.

> 3. How reliably does NFS work as a root file system, if the NFS server
> goes down and up?  I had trouble using NFS to serve up
> videos/posters/pictures until I started using autofs.

If the NFS server is not reliable, then either running the root file 
system from a local drive (whether magnetic or flash) or from RAM might 
be a better choise.