[ANNOUNCE] v5.0.3-rt1

[Sebastian Andrzej Siewior]

Dear RT folks!

I'm pleased to announce the v5.0.3-rt1 patch set. 

Changes since v4.19.25-rt16:

  - rebase to v5.0

  - Several ARM architectures have a so called "boot_lock" in their SMP
    bring up code. In previous releases the boot_lock was converted to
    to a raw_spinlock in order to get in working on -RT. As of v5.0 only the
    bits for the `versatile' platform have been applied upstream and I
    dropped the patch entirely.
    The other platforms were rejected because they were doing it wrong by
    using such a lock. The omap2 and sti platform were converted to other
    mechanism as part of the discussion. Others (like i.MX) were never
    using such a lock.
    There are still a few platforms using such a lock. If you are
    affected you would to convince the platform maintainer to remove the
    lock from the SMP code.

  - Applied John Ogness' prinkt rework. One visible change is the
    output during boot. Under the hood and for RT: By default, output
    that is created at KERN_WARN[0] or higher is printed immediately if the
    console supports "atomic" print (currently the 8250 driver does).
    This output is printed immediately (and visible) even from IRQ-off
    or preempt-disabled regions which wasn't the case earlier. This will
    raise the latency at run-time *but* there should be no WARNING,
    ERROR or PANIC messages at run-time on a fully working system.
    Messages with lower severity are printed "later" by a kthread.

    [0] default message level, default_message_loglevel, second field in
	/proc/sys/kernel/printk

  - Applied "restore FPU on return to userland" series. This only
    applies to x86. This change makes repeated kernel_fpu_begin() +
    kernel_fpu_end() cheap.

  - I tried to include some BH related rework but it is not yet in
    reasonable shape. I will probably revisit this during the v5.0
    cycle.

Known issues
     - A warning triggered in "rcu_note_context_switch" originated from
       SyS_timer_gettime(). The issue was always there, it is now
       visible. Reported by Grygorii Strashko and Daniel Wagner.

     - rcutorture is currently broken on -RT. Reported by Juri Lelli.

You can get this release via the git tree at:

    git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v5.0.3-rt1

The RT patch against v5.0.3 can be found here:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.0/older/patch-5.0.3-rt1.patch.xz

The split quilt queue is available at:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.0/older/patches-5.0.3-rt1.tar.xz

Sebastian