a new kind of fake-PAE may be entered into the main-stream 32-bit kernel

Nio Wiklund nio.wiklund at gmail.com
Mon Mar 3 19:35:58 UTC 2014

Hi Lubuntuers,

A new kind of fake-PAE may be entered into the main-stream 32-bit
kernel, and I think this long-lasting bug will finally be squashed :-)

Please test it if you have a suitable computer and you have time!

If you want to take a short-cut and use an OBI tarball, let me know, and
I'll upload it for you.


The conversation below is from this link about PAE problems for Pentium
M and Celeron M computers


Best regards

Chris Bainbridge (chris-bainbridge) wrote on 2014-03-01: 	#274

There's a new pair of patches: https://lkml.org/lkml/2014/2/28/258 and

It's a small patch but test reports to LKML are still welcome (you don't
have to be subscribed to the list to respond, just use the correct
subject line).

roland aus köln (devzero-c) wrote on 2014-03-02: 	#275

i just tested your patch on ubuntu 13.10 with kernel from 14.04
repository (complete package build)

works like a charm!

i would recommend adding the newly introduced param to to
Documentation/kernel-parameters.txt , see my patch at


Thanks for your work !

Andy Whitcroft (apw) wrote 6 hours ago: 	#276

@Chris -- I have taken the liberty of cleaning up the commentary on
those two patches and applying them to a 14.04 kernel for testing. You
might want to do something similar (feel free to steal the text I used
and clean it up) and then submit the patches together to upstream for
consideration; as things have been left I doubt they will be applied as
the diff and commentary were separate. Also could you test these kernels
and let me know if they work at all, I do not have affected h/w. We can
then consider this for the 14.04 kernel. Kernels are at the URL below:


roland aus köln (devzero-c) wrote 4 hours ago: 	#277

works for me.

sudodus (nio-wiklund) wrote 1 hour ago: 	#278

Works in my IBM Thinkpad T42 with Pentium M without a PAE flag but with
PAE capability.

But I have only booted via grub, because I cannot remaster an iso file.
Did you boot from syslinux, Roland?

Chris Bainbridge (chris-bainbridge) wrote 1 hour ago: 	#279

lkml: "grub is jumping to the 32-bit entry point and skipping the entire
real mode setup code. Bad grub."

You don't need to build a syslinux bootable iso. You can boot the kernel
from Grub in 16-bit mode by using the linux16 command
http://www.gnu.org/software/grub/manual/html_node/linux16.html and
initrd16 https://www.gnu.org/software/grub/manual/html_node/initrd16.html

According to the discussion on LKML, linux16 is now the default on
Fedora, and should be used by other distributions.

(If you still want to build a custom syslinux bootable system, just for
fun, see the instructions at
http://willhaley.com/blog/create-a-custom-debian-live-environment/ -
it's about 25 lines of code in total, and not difficult to follow)

sudodus (nio-wiklund) wrote 21 minutes ago: 	#280

ERROR: PAE is disabled on this Pentium M
(PAE can potentially be enabled with kernel parameter
"forcepae" - this is unsupported, may cause unknown
problems, and will taint the kernel)
This kernel requires the following features not present on the CPU:
Unable to boot - please use a kernel appropriate for your CPU


So I used the following modified lines in grub.cfg

 linux16 /boot/vmlinuz-3.13.0-14-generic root=UUID="string" ro quiet
splash forcepae $vt_handoff
 initrd16 /boot/initrd.img-3.13.0-14-generic

and it boots and runs :-)

WARNING: Forcing PAE in CPU flags

Thanks Chris :-)
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