[syslinux] Help with PXE "Out of Memory" error?

[Gene Cumm]

On Sun, Oct 1, 2017 at 8:00 PM, Locane via Syslinux <syslinux at zytor.com> wrote:
> Hello all!  I have a server at work that we're using for PXE OS
> installation and LiveCD loading.  It's based on CentOS 7.3, and CentOS
> comes with Syslinux version 4.05.

Thanks for noting the version.  Are they the binaries from CentOS?

> We've been having this issue, very rarely, with some systems that refuse to
> load a LiveCD from the menu, claiming they're "out of memory" when we know
> that is absolutely not the case; there's plenty of RAM.  This video
> <https://www.youtube.com/watch?v=y-rfNxA4VH0&feature=youtu.be> is of a
> Supermicro H11DSU-iN motherboard throwing the error on LiveCD load.

It's partially true.  It's out of memory in the spot it attempted to
load the files.  Are your logs verbose enough to see how much data of
the initrd is actually transferred?  If not, have you attempted a
packet capture to see how much is moved?

> To be clear, we've had literally thousands of diverse other systems and
> servers run this LiveCD menu option with no issues; it's just this
> motherboard and weirdly, any Celeron-based Intel NUCs - the NUC6CAYH.

It's all about how the underlying firmware sets things up.

> If no one has any ideas on why this might be happening, is there a guide or
> tutorial on how to set up a newer version of the Syslinux PXE files under
> CentOS 7.3?  I've been taking stabs at it by just replacing the 3 files
> documented in the Syslinux PXELINUX wiki page
> <http://www.syslinux.org/wiki/index.php?title=Install#PXELINUX>, but it's
> behaving weirdly and, frankly, I'm kinda just taking stumbling around in
> the dark here.
>
> Would appreciate some expert advice.

meminfo.c32 should give more insight.

linux.c32, although a lot less verbose during the loading of files,
should be more intelligent in how it attempts to load files into
memory.

LABEL livecd
  MENU LABEL LiveCD_Unstable
  LINUX /images/LiveCD_Unstable/unstable_vmlinuz
  APPEND initrd=/images/LiveCD_Unstable/unstable_initrd.img my-options-here

LABEL livecd1
  MENU LABEL LiveCD_Unstable1
  COM32 linux.c32
  APPEND /images/LiveCD_Unstable/unstable_vmlinuz
initrd=/images/LiveCD_Unstable/unstable_initrd.img my-options-here

-- 
-Gene