kernel-packages team mailing list archive

[Chris Bainbridge <chris.bainbridge@xxxxxxxxx>]

Jii wrote:
> No, I was not booting with forcepae option. After installer, the system was fully operational so I didn't know there was need to add it.

How did you boot the installer? Normally syslinux will boot the kernel
in 16-bit mode and you would get the forcepae error message.

Andy Whitcroft wrote:
> If the kernel is booted, then forcepae must have been supplied

This is not always true. A PAE kernel will boot on a PAE capable Pentium
M without forcepae if the boot loader skips the 16-bit entry code of the
Linux kernel. This is the case with a default install of grub on Ubuntu
- which is why many Pentium M users who had installed Ubuntu before the
switch to PAE-only didn't have any problems when they got upgraded (but
later ran into problems when the check for pae in /proc/cpuinfo was
added to the linux-image preinst). You can force grub to boot the kernel
in 16-bit mode by using the linux16 and initrd16 commands instead of
plain linux and initrd; using the 16-bit boot path seems to be
preferred by upstream since then the kernel CPU checks get run, but it
is probably too late for Ubuntu to switch.

Daniel Letzeisen wrote:
> Should the ubiquity installer do a special check to see if it's been s tarted with forcepae

Could do, the check is not hard (running pae kernel and (forcepae or no
pae in cpuinfo flags).

It would be nice for the user to not have to bother with forcepae; I
would have preferred to enable it automatically rather than having the
kernel parameter, but the x86 maintainers thought that a user should
have to consent to operating their CPU out of spec. If Ubuntu were happy
with assuming consent, then you could just add it to the default pae-
kernel boot parameters and make the whole thing invisible to the user.

-- 
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1307105

Title:
  Kernel install fails due PAE checks

Status in “linux” package in Ubuntu:
  Triaged

Bug description:
  [TRIAGE NOTE]
  When a user boots Ubuntu Live/Install media with 'forcepae' option, the option should automatically be added to /etc/default/grub, or kernel upgrades will refuse to install when they do not see pae capability in cpuinfo.

  [ORIGINAL REPORT]
  On Thinkpad T42 with Pentium M processor linux image upgrade fails with message "This kernel does not support a non-PAE CPU.". System was installed from  ubuntu-14.04-beta2-desktop-i386.iso with "forcepae" kernel option. After install, system works, but cannot be upgraded to laters kernel.

      root@t42:/boot# apt-get upgrade
      Reading package lists... Done
      Building dependency tree
      Reading state information... Done
      You might want to run 'apt-get -f install' to correct these.
      The following packages have unmet dependencies:
       linux-image-extra-3.13.0-24-generic : Depends: linux-image-3.13.0-24-generic but it is not installed
       linux-image-generic : Depends: linux-image-3.13.0-24-generic but it is not installed
      E: Unmet dependencies. Try using -f.

      root@t42:/boot# apt-get install -f
      Reading package lists... Done
      Building dependency tree
      Reading state information... Done
      Correcting dependencies... Done
      The following extra packages will be installed:
        linux-image-3.13.0-24-generic
      Suggested packages:
        fdutils linux-doc-3.13.0 linux-source-3.13.0 linux-tools
      The following NEW packages will be installed:
        linux-image-3.13.0-24-generic
      0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
      3 not fully installed or removed.
      Need to get 0 B/14.6 MB of archives.
      After this operation, 32.3 MB of additional disk space will be used.
      Do you want to continue? [Y/n]
      (Reading database ... 196089 files and directories currently installed.)
      Preparing to unpack .../linux-image-3.13.0-24-generic_3.13.0-24.46_i386.deb ...
      This kernel does not support a non-PAE CPU.
      dpkg: error processing archive /var/cache/apt/archives/linux-image-3.13.0-24-generic_3.13.0-24.46_i386.deb (--unpack):
       subprocess new pre-installation script returned error exit status 1
      Examining /etc/kernel/postrm.d .
      run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.13.0-24-generic /boot/vmlinuz-3.13.0-24-generic
      run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.13.0-24-generic /boot/vmlinuz-3.13.0-24-generic
      Errors were encountered while processing:
       /var/cache/apt/archives/linux-image-3.13.0-24-generic_3.13.0-24.46_i386.deb
      E: Sub-process /usr/bin/dpkg returned an error code (1)

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