Upgrade linux-rt to 2.6.27

This is _crucial_ for Ubuntu Studio. We are very close to have to (for the first time) make a release without a real time kernel. If we can get a freeze exception though, the linux-rt of 2.6.27 will be ready for release.

Only a few minor issues in amd64 which are being solved already.

I agree. Without linux-rt, Ubuntu Studio cannot be released... Although for me it doesn't matter if this bug is solved by upgrading all packages to .27, or downgrading all to .26 - as long as we can use a recent rt kernel in Intrepid...

What currently happens when trying to install linux-rt in Intrepid:
$ LANG=C sudo apt-get install linux-rt
...
The following packages have unmet dependencies:
  linux-rt: Depends: linux-restricted-modules-rt (= 2.6.26.1.5) but it is not going to be installed
E: Broken packages

@Alessio: You probably know this, but your version is not installable currently due to a lack of linux-restricted-modules-2.6.27-2-rt installation candidate. Log attached.

@Motin,

At the moment meta-packages as linux-rt, linux-image-rt and
linux-headers-rt are only placeholders without effects.

If you want install kernel from my PPA you should execute this command:

sudo apt-get install linux-image-2.6.27-2-rt

Please go ahead with 2.6.27. It brings in huge improvements and we are actually unable to install -rt flavour kernels in Intrepid.

ACK from me, but with some reservations, hopefully which can all be fixed in SRUs.

 * On two notebooks I have here, I cannot restart/shut down with the rt kernel on either of them, one amd64, one i386.
 * Only one core of any CPU can currently be used.
 * Network Manager causes a lot of xruns at least for me, even with a high period size setting jack.

 affects ubuntu/linux-rt
 status confirmed

This bug was fixed in the package linux-rt - 2.6.27-3.7

---------------
linux-rt (2.6.27-3.7) intrepid; urgency=low

  * Synced against linux-source-2.6.27 2.6.27-7.12
  * Added ext4-nrpages.patch and jbd2-nrpages.patch
  * Synced configuration

linux-rt (2.6.27-3.6) intrepid; urgency=low

  * Synced against linux-source-2.6.27 2.6.27-7.11

linux-rt (2.6.27-3.5) intrepid; urgency=low

  * Synced against linux-source-2.6.27 2.6.27-7.10
  * Bump ABI to -3

linux-rt (2.6.27-2.4) intrepid; urgency=low

  * Mistake in packaging

linux-rt (2.6.27-2.3) intrepid; urgency=low

  * Fix a FTBS

linux-rt (2.6.27-2.2) intrepid; urgency=low

  * Synced against linux-source-2.6.27 2.6.27-6.9
  * Disable CONFIG_AUFS, CONFIG_CGROUP_MEM_RES_CTLR, CONFIG_FTRACE,
    CONFIG_LATENCYTOP, CONFIG_CONTEXT_SWITCH_TRACER
  * Set timer frequency to 1000 HZ
  * Bump ABI to -2

linux-rt (2.6.27-1.1) intrepid; urgency=low

  * Initial version based on linux-source-2.6.27 2.6.27-4.6 (LP: #281276)

 -- Alessio Igor Bogani <email address hidden> Sat, 18 Oct 2008 18:08:55 +0200

linux-rt 2.6.27-3.7 accepted into intrepid.

I hope I'm not stepping on toes reopening this. I wasn't able to find guidelines about already closed reports.

Using the linux-rt 2.6.27-3.8 released yesterday I still have at least some of the issues listed in the above comment by Luke Yelavich (https://bugs.launchpad.net/ubuntu/+source/linux-rt/+bug/281276/comments/6).

Only one CPU is used and shutdown/restart do not work. Perhaps of note is that the rt variant does not set CONFIG_NR_CPU which is set to 64 in 2.6.27-7-generic and 8 in the old 2.6.24-21-rt and also does not set CONFIG_SMP which set to y on the others.

After booting 2.6.27-3-rt dmesg contains this line:

[ 0.000000] WARNING: NR_CPUS limit of 1 reached. Processor ignored.

Compared to booting the non-rt 2.6.27-7-generic:

[ 0.000000] SMP: Allowing 2 CPUs, 0 hotplug CPUs
[ 0.000000] PERCPU: Allocating 64928 bytes of per cpu data
[ 0.000000] NR_CPUS: 64, nr_cpu_ids: 2, nr_node_ids 1

Thomas, the issues listed are more appropriate as a separate bug report.

Makes sense. Opened #290498