Re: [PATCH RT] don't let printk unconditionally turn on interrupts

[Ingo Molnar]

* Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> Ingo,
> 
> My first try at booting -rt8 on my machine crashed immediately.  No 
> nmi, no nothing. Just a lockup at the registration of the ACPI_PM 
> timer. This would happen every time, and after struggling for a while, 
> I finally found out why!
> 
> The printk in timeofday_periodic_hook that is called holding the 
> write_lock of system_time_lock (a raw_seq_lock) was causing lots of 
> havoc.  The printk would turn on interrupts, and then I would get a 
> deadlock when the interrupt would do a read on system_time_lock.

argh. This piece of code has caused so many problems already. Some 
people want console drivers to be preemptible, but i guess being able to 
boot trumps things ;)

could you check out the variant in 2.6.15-rt11 - i tweaked it slightly 
over yours, hopefully making the behavior more consistent.

	Ingo
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