[syslinux] iPXE chain to lpxelinux.0 6.03-pre17 inconsistencies and failures

[Gene Cumm]

On Jul 1, 2014 10:37 PM, "Alexander Perlis" <aperlis at math.lsu.edu> wrote:
>
> I believe I'm seeing a bug in lpxelinux.0 6.03-pre17 but I need some
advice on how to isolate and troubleshoot this. (I can't try pre18 at the
moment, but did try 4.07 and 5.10 and saw similar behavior, also with
pxelinux.0, so although I'll give pre18 a try soon, some
isolation/troubleshooting advice will be a good education no matter what.)

Odd. 4.07 should be good but the 4.10/5.1*/6.0* revisions make sense.

> To get to our PXE-launched tools from hosts on a subnet without proper
DHCP support (e.g., on a NAT or in a different building), we're trying to
use small iPXE USB thumb drives and/or iPXE CD-ROMs, obtained from
rom-o-matic.eu, which then chainload to lpxelinux.0 off our actual PXE
server. (We used pxelinux-options to put a "-b pxe.ip.address" into
lpxelinux.0, so that it would know the server IP for grabbing the
subsequent libxxx and config files.)
>
> On some hosts we successfully get all the way to the graphical
vesamenu.c32 under lpxelinux.0, while on other hosts we reach the initial
lpxelinux.0 banner line but then the host hangs (and server shows no
attempt to grab libxxx or config files), while on other hosts there is a
reboot as soon as control is handed to lpxelinux.0 (and unclear whether the
banner line is printed, as the reboot blanks the screen too quickly).
>
>  Intel Macs: local-ipxe->lpxelinux.0->banner->vesamenu.c32->success
>  Dell GX620: local-ipxe->lpxelinux.0->banner->hang
>  Dell 780:   local-ipxe->lpxelinux.0->instant-reboot
>
> I'm not sure how to dig deeper. I'm using the precompiled binaries. Is it
easy to compile a debug version that spits out verbose progress prior and
after the banner and perhaps pauses for user input?
>
> I'm guessing ipxe is somehow setting the stage in a way that is caught by
something finicky in lpxelinux.0 on certain hardware, or perhaps there's a
bug in how ipxe sets the stage. Just to eliminate that latter variable, any
recommendations for a non-ipxe-way to boot off a CD or USB to then PXE-boot
to a specific server (not via DHCP)?

This is probably related to a bisect I did recently. I found the culprit
commit in my case but a blind revert feels wrong.

--Gene