[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

[Bernd Kreuss]

The affected Pentium-M CPUs of these not so old Laptops all have phyical
address space of 36 bits but for some reason Intel decided to not set
the PAE flag (maybe its a bug in these series of CPU itself?) These were
very popular CPUs at that time and they were built into a lot of
Laptops, including many of the legendary ThinkPad models of that time,
many of which are still in use today.

I can confirm that the PAE-Kernel will boot and run on these machines
without any problems.

There are currently 2 Problems that make it extremely hard for people to use these kernels:
(1) the syslinux bootloader will refuse to boot from the install CD (although it could if it would at least try)
(2) the install scripts in the kernel .deb packages will simply grep -q ' pae ' /proc/cpuinfo and fail with error

The problem in (2) can be hacked around by the desperate user by simply
bind-mounting a faked /proc/cpuinfo that contains this flag and then one
can happily upgrade to 12.10 and install and use these new pae kernels
without the slightest problem. It should be fixed by making the check in
the install script in these kernel .deb packages more elaborate, maybe
instead of grepping for pae it should grep for "36 bits physical" or
these few very popular CPUs should simply be whitelisted.

The problem in (1) should be fixed in the way syslinux detects this
(maybe counting the physical address bits instead of looking for the
flag or simply whitelisting these few CPUs that actually have PAE and
just not announce it in their flags would be a good idea?)

It wouldn't be such a problem if it were only old and exotic hardware
but this bug also affects all the popular ThinkPads that are not so old
and still in use today! These devices are for example still used today
in the international space station (ISS) (they actually are the *only*
Laptops officially certified for space travel and Ubuntu does not want
to support them anymore) Richard Stallman (GNU) has been seen with
ThinkPads on multiple occasions and even Shuttleworth (Canonical)
himself has been photographed on board of the ISS using a ThinkPad. You
cannot simply ignore this entire class of wonderful and useful Devices.

https://www.google.de/search?q=iss%20thinkpad

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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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