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2015-10-05 12:00

Real-time Linux on the go!

Real-time capabilities of the mainline Linux kernel - also known as PREEMPT_RT patches - have a long and predominantly successful history. It is ...

2014-11-18 00:00

Linux real-time: New stable release available -

but next one depends on more support from industrial users

2014-04-09 12:00

First LCA certificate issued

Major automation provider passed OSADL License Compliance Audit

2008-07-29 12:00 Age: 7 Years

A new RTOS is born

By: Carsten Emde

Our latest and greatest Linux RT-Preempt (linux- is now our "Latest Stable".

When on Friday, January 25, 2008, we wrote "Kernel 2.6.24 on its way to the next 'Latest Stable'" we were absolutely right that it was "on its way". But who had believed at this time that it would take more than six months to finally release it as "Latest Stable"?

No other release has been tested so heavily on so many different architectures and under so many different conditions as this one. This is the best mainline Linux real-time we ever had, and it is another important milestone in the creation of a new RTOS: Linux.

Important note: Do not expect the RT-Preempt patches for kernel version 2.6.25 to be made ready for production. We move on to 2.6.26!

And here is a little excuse why this "Latest Stable" took so long. The following list contains all individual fixes that have been applied since the release of the first RT-Preempt patches based on 2.6.24:

• compiler warning fix (Shi Weihua)
• updates to ftrace (Ingo Molnar, Steven Rostedt)
• root domain kfree fix (Gregory Haskins)
• event trace compile fix (Clark Williams)
• kthread cpus_allowed init (Gregory Haskins)
• migration CPU_DYING case  (Gregory Haskins)
• PPC preempt disable tlbflush (Egor Starkov)
• printk hack fix  (Steven Rostedt)
• preemption during spinlock (Gregory Haskins)
• slab cpu fix (Hiroshi Shimamoto)
• swap deadlock fix (Hiroshi Shimamoto)
• sysctl compile fix (Leon Woestenberg)
• move update_wall_time back to interrupt (Thomas Gleixner)
• cache pci_find_capability (Arnaldo Carvalho de Melo)
• removal of printks from ftrace max hits (Steven Rostedt)
• send NMI after nmi_show_regs (Hiroshi Shimamoto)
• return true for NMI handler (Hiroshi Shimamoto)
• NMI for irq_show_regs_callback (Hiroshi Shimamoto)
• wait for finish show_regs before panic (Hiroshi Shimamoto)
• avoid deadlock related swap_lock (Hiroshi Shimamoto)
• shorten softirq thread names (Peter Zijlstra)
• push RT tasks after newly activated (Gregory Haskins)
• GCC 4.3 kernel linker error (Carsten Emde)
• Kconfig trace histogram typo fix (Carsten Emde)
• lateral lock stealing (Gregory Haskins)
• rtmutex rearrange logic (Gregory Haskins)
• rtmutex remove double xchg (Steven Rostedt)
• adaptive spinlocks (Gregory Haskins, Sven Deitrich, Peter Morreale, Steven Rostedt)
• Read Write locks with multiple readers (Steven Rostedt)
• RT downgrade_write (Steven Rostedt)
• fix RT rwlocks typecasts (Steven Rostedt)
• default sched_nr_migrate to 8 (Steven Rostedt)
• ftrace task comm fix (Steven Rostedt)
• ARM compile fix (Remy Bohmer)
• ported latest ftracers (Steven Rostedt)
• vdso vsyscall generic (Luis Goncalves)
• git-ignore update (Hiroshi Shimamoto)
• lockstat updates (Peter Zijlstra)
• adjust pi_lock in wakeup waiters (Peter Morreale)
• optimize rt_spin wakeup (Peter Morreale)
• all archs use task->oncpu (Gregory Haskins, modified use in header by Steven Rostedt)
• remove redundant try_to_take_lock (Peter Morreale)
• fastpath try_to_take_lock on steal (Steven Rostedt)
• ticket FIFO spinlocks (Nick Piggin)
• preempt __delay fix (Steven Rostedt)
• load_balance breaks (Peter Zijlstra)
• ftrace minor fixes (Steven Rostedt, Clark Williams, Abhishek Sagar)
• disable ftrace daemon (Steven Rostedt)
• sched_rt migration updates (Gregory Haskins)
• nmi show regs fix (Hiroshi Shimamoto)
• trace histogram divide by zero fix (Carsten Emde)

• trace histogram late divide (Carsten Emde)
• rwlock priority leak fix (Steven Rostedt)
• rwlock pi_list fixes (Steven Rostedt)
• rwlock torture test module (Steven Rostedt)
• events tracer clocksource program event hook (Steven Rostedt)
• ftrace wakeup schedule raw spinlock (Steven Rostedt)
• radix tree lockdep annotation fix (Steven Rostedt)
• sched_cpupri hotplug support (Gregory Haskins)
• sched_cpupri prio count (Gregory Haskins)
• ftrace hotplug fix (Steven Rostedt)
• revert adaptive locks from RCU (Thomas Gleixner)
• rwlock mutex owner fix for waking up reader with readers held (Steven Rostedt)
• rwlock remove waiter from pi_list on above fix (Steven Rostedt and Thomas Gleixner)
• rwlock replace macro with inline (Thomas Gleixner)
• rwlock pending namespace updates (Thomas Gleixner)
• rwlock debug check (Thomas Gleixner)
• futex fix fault (Thomas Gleixner)
• x86_64 fix copy user (Linus Torvalds)
• add support for m68knommu (Sebastian Siewior)
• various general mainline bugfixes collected by Clark Williams
• mm fix race in COW logic (Nick Piggin)
• various hrtimer/nohz bugfix backports (Thomas Gleixner)
• command line option to supply the acpi pmtimer port  (Thomas Gleixner)
• rtmutex debug fix (John Stultz)
• CPU hotplug fixes (Peter Zijlstra)
• rt rwlock locking fixes (Steven Rostedt)
• ftrace function pointer fix (Josh Triplett)
• RCU memory barrier fix (Paul McKenney)
• scheduler: round robin time slice fix (Miao Xie)
• frace: preempt trace fix (Steven Rostedt)
• scheduler: SCHED_FIFO spec violation fix (Peter Zijlstra, Darren Hart)
• PPC64 fixes (Chirag Jog, Sebastian Dugue)
• load average calculation fix (Michal Schmidt)
• ftrace: do not wakeup the waitqueue when interrupts disabled  (Thomas Gleixner)
• ACPI: fix reschedule checks (Thomas Gleixner)
• smp boot hotplug fix (Peter Zijlstra)
• scheduler: fix race of dequeued SCHED_RR task against timer interrupt  (Thomas Gleixner)
• scheduler: round robin time slice fix (Miao Xie)
• remove m68knommu merge artifacts (Thomas Gleixner)
• fix x86_64 UP build (Peter Zijlstra)
• powerpc ftrace backport (Thomas Gleixner)
• fix long standing NFS missing preemption check (Thomas Gleixner)