[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

[Dmitrijs Ledkovs]

On 27 November 2013 10:42, roland aus köln <devzero at web.de> wrote:
> i don`t have the skills for this and i don`t understand, why hpa
> forwarded discussion to lkml at this early stage, as it is a patch
> primary meant for the ubuntu kernel to adress an ubuntu specific
> problem.
>

I understand your concern. The fact that certain CPUs are buggy and do
not declare PAE capability is a hardware bug which cannot be rectified
and if quirks are needed on the kernel side, the right way is to
essentially white-list / set PAE options of the affected CPUs.

ubuntu kernels do not typically apply original patches, mostly only
cherrypicks from upstream trees/vendors.

> sure it is not perfect and not the optimal way to proceed, but it is a
> solution to a problem.
>
> we wouldn`t have this problem and we wouldn`t have this patch if there
> wasn`t the discision to drop support for non-pae kernels.
>
> so hopefully the ubuntu kernel maintainers will give a comment on this
> patch or pick it up to make a version which fulfils kernel code-
> quality/style or patch-submission requirements.
>
> this patch is rather unintrusive and it easily solves a problem for many
> users.  i spend many hours on debugging this issue and developing this
> patch, so for now please understand that i`m done with it.
>
> lkml reference:  http://marc.info/?l=linux-kernel&m=138550884425543&w=2
>

I understand your concerns, and I'll talk to kernel team, to see if we
can get this properly worked out and upstreamed.

Regards,

Dmitrijs.

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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 “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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