[syslinux] run pxelinux.0 on a booted system

[H. Peter Anvin]

Carl Karsten wrote:
> Carl Karsten wrote:
>> I am trying to come up with a 'clever' way to pxe-boot boxes that don't have any 
>> way to pxe boot.  as in, old laptops that only have pc-mica nics.
>>
>> "Etherboot does not (yet) offer support for PCMCIA cards." 
>> http://www.etherboot.org/wiki/pcmcia_support
>>
>> I am not trying to do 'that' - just trying to come up with a process to work 
>> around it.  Something like this:
>>
>> Boot a Live CD.  (eventually one I customize with a nifty script to do all of 
>> this)  Now I have support for my pcmica nic.
>>
>> Now do the part that PXE would do:
>>
>> dhcpclint, get an IP, netmask etc.
>> and a file name (pxelinux.0) and maybe a server name.
>>
>> use tftp client to get that file:
>> juser at v550b:~$ tftp shaz
>> tftp> get pxelinux.0
>>
>> run it.
> 
> I doubt this will work:
> 
> I am pretty sure pxelinux.0 wants to run in real mode.
> 
> Normally: the nic rom runs in real mode, it is the nic driver for pxelinux.0
> I was thinking it was OK because I would never "return from pxelinux.0 to the 
> OS" and so it wouldn't matter if I somehow flipped into real mode.
> I don't "come back" from pxelinux.0, but it does call into the OS, which .. 
> won't be anything it can call into anymore
> I was relying on the OS's pcmica nic support to get around "no pcmcia nic pxe" 
> but the OS is all protected mode and so this isn't going to work, right?
> 

Not only is the mode all wrong, but pxelinux.0 runs on top of the BIOS 
and PXE APIs, not on top of Linux.

However, if you want to do the above, you need to use kexec.

	-hpa