[PATCH 0/3] Allow to enable PREEMPT_RT.

[Sebastian Andrzej Siewior]

The printk bits required for PREEMPT_RT are sitting in linux-next. This
was the last known roadblock for PREEMPT_RT. The RT queue has
additionally the "atomic console" for the 8250 UART which is not yet in
linux-next. This means "legacy console" behaviour as in no printing from
atomic context in emergency cases. The 8250 UART driver is the only one
providing "atomic console" support as of today.

With the printk bits merged, PREEMPT_RT could be enabled on X86, ARM64
and Risc-V. These three architectures merged required changes over the
years leaving me in a position where I have no essential changes in the
queue that would affect them.
ARM and POWERPC have a few essential patches left and I lost track of
MIPS.

Sebastian