2.6.38-11-generic re-introduced old bug on Gateway FX6850-51u

[Aleksandar Milivojevic]

On Mon, Aug 22, 2011 at 9:44 AM, Aleksandar Milivojevic
<alex at milivojevic.org> wrote:
> It looks like 2.6.38-11 re-introduced old bug, where kernel would hang
> on halt or reboot.  The bug was present on the original kernel shipped
> with Ubuntu 11.04 (2.6.38-8, if my memory serves me right), and fixed
> in the very next kernel update.  However, with 2.6.38-11, the problem
> is back.
>
> In short, at the very end of shutdown sequence, after all file systems
> were unmounted, etc, kernel would simply hang.  User have to
> long-press power button to physically power cycle the system in order
> to recover.  In my case this was mostly an annoyance, but for other
> users it may be much more serious problem, as it makes system
> impossible to reboot remotely (for obvious reasons).
>
> My system is an Gateway FX6850-51u, with 3.4GHz Intel Core i7-2600
> Sandy Bridge quad-core processor, 8GB DDR3 RAM.  It has an Accer
> branded motherboard (no identifier of exact motherboard version
> printed anywhere on it).  Gateway's website has full system specs
> (http://us.gateway.com/gw/en/US/content/model/PT.GBN02.012).  The only
> difference from stock system as sold by Gateway is PCI-e WiFi card
> removed and replaced with an USB WiFi stick, and hard drive replaced
> with an SSD drive.
>
> I saw few older discussions on the mailing list mentioning same
> problem on some other systems as well (for example, Dell's).
>
> I'd provide a bit more info, however once the system is power cycled,
> there's not much left on the system itself.

Actually, thinking about it, it may also be switching between grub-pc
and grub-efi.  Originally, Ubuntu 11.04 installer put grub-efi on the
system.  On next kernel update (where halting/rebooting problem was
fixed), updater replaced grub-efi with grub-pc.  Now, while system was
not hanging on shutdown anymore, grub-pc introduced bunch of other
problems during booting up the system, making booting up the system
unreliable (installer partitioned and configured the system originally
as an EFI system, so switching back to grub-pc broke things, as it
doesn't seem to know about EFI).  Then, after last kernel upgrade, I
switched back to grub-efi.  Switching back to grub-efi fixed booting
up the system, error messages when running grub-update (or
grub-install) are gone, but now system hangs again on shutdown.

I'm bringing this up, since I think I was actually able to reboot the
system without it hanging once or twice between applying last kernel
upgrade, and switching back to grub-efi.

I'm not sure how and why would choice of boot loader (grub-pc vs.
grub-efi) affect shutting down the system, but it looks like it does
in some odd way!?