[Bug 930447] Re: Unable to start Ubuntu 12.04 live CD with syslinux loader on Pentium M x86 Laptop due to bug in PAE kernel, initramfs or syslinux

[Mantas Kriaučiūnas]

Syslinux contains some code (modules), that checks the CPU flags, like PAE support or for 64-bitness and loads the appropriate label in a pxelinux.cfg file. See
http://git.kernel.org/?p=boot/syslinux/syslinux.git;f=com32/modules/ifcpu.c;hb=HEAD
http://syslinux.org/wiki/index.php/Ifcpu64.c32

It seems Ubuntu doesn't use this syslinux feature, could Ubuntu developers tell us where is the problem? Why PAE kernel works fine when GRUB is used, but reports an error about missing PAE when syslinux is used?
Maybe syslinux boot loader forces some CPUs not to work with PAE kernel (maybe some CPUs can work either in PAE mode or not PAE mode?) or maybe syslinux reports to the PAE kernel, that CPU doesn't support PAE?

In any case this syslinux bug should be fixed ASAP - lots of people now
can't even start Ubuntu 12.04, while all other versions and most other
Ubuntu-based distros (like LinuxMint 13) work fine.

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https://bugs.launchpad.net/bugs/930447

Title:
  Unable to start Ubuntu 12.04 live CD with syslinux loader on Pentium M
  x86 Laptop due to bug in PAE kernel, initramfs or syslinux

Status in “linux” package in Ubuntu:
  Won't Fix
Status in “syslinux” package in Ubuntu:
  Confirmed
Status in Baltix GNU/Linux:
  Triaged

Bug description:
  Ubuntu 12.04 doesn't start from Desktop CD or USB with syslinux boot
  loader on Pentium M 1.6Ghz or faster Pentium M CPU - displays error
  message about missing PAE feature in CPU, but *the same* *Ubuntu
  12.04* Desktop CD/LiveUSB starts fine on *the same CPU* (and same PAE
  kernel) if GRUB boot loader is used, for example when WUBI or LiveUSB
  with GRUB boot loader, like Multisystem
  (http://liveusb.info/dotclear/index.php?pages/install ) is used!

  The error message is:
  "This kernel requires the following features not present on the CPU: pae.
  Unable to boot - please use a kernel appropriate for you CPU."

  THIS IS AN IMPORTANT REGRESSION! People are able to install and successfully use Ubuntu 12.04 on such pretty new hardware, like IBM Thinkpad T42 laptop with Pentium M 1700Mhz processor, but the bug in syslinux (or something related) forbids Ubuntu 12.04 installation.
  This bug is reproducible on lots of computers, there are several log files and /proc/cpuinfo file attached to this bugreport, AFAIK it's enough to reopen this bug.

  ---
  ApportVersion: 1.23-0ubuntu4
  Architecture: i386
  CurrentDmesg: Error: command ['sh', '-c', 'dmesg | comm -13 --nocheck-order /var/log/dmesg -'] failed with exit code 1: comm: /var/log/dmesg: Permission denied
  MachineType: IBM 2373PPU
  dmi.bios.date: 06/18/2007
  dmi.bios.vendor: IBM
  dmi.bios.version: 1RETDRWW (3.23 )
  dmi.board.name: 2373PPU
  dmi.board.vendor: IBM
  dmi.board.version: Not Available
  dmi.chassis.asset.tag: No Asset Information
  dmi.chassis.type: 10
  dmi.chassis.vendor: IBM
  dmi.chassis.version: Not Available
  dmi.modalias: dmi:bvnIBM:bvr1RETDRWW(3.23):bd06/18/2007:svnIBM:pn2373PPU:pvrThinkPadT42:rvnIBM:rn2373PPU:rvrNotAvailable:cvnIBM:ct10:cvrNotAvailable:
  dmi.product.name: 2373PPU
  dmi.product.version: ThinkPad T42
  dmi.sys.vendor: IBM

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