buildworld panic on ia64

[Anton Shterenlikht]

On Tue, Jul 07, 2009 at 05:29:06PM -0700, Marcel Moolenaar wrote:
> 
> On Jul 7, 2009, at 6:36 AM, Rink Springer wrote:
> >> I tried to reproduce the error, got this on the way:
> >>
> >> 	# XXX: bogusly disabled high FP regs
> >
> > I get this message quite often as well; I intend to figure out what's
> > going on. Marcel, if you have any idea, please let me know.
> 
> It's a race condition. The high FP registers are lazily
> context-switched and this error is emitted when a thread
> wants to use the high FP registers when they are disabled
> and the CPU onto which the thread is running has the high
> FP registers corresponding to that thread in registers.
> In that scenario the high FP registers should not even be
> disabled.
> 
> In the above case the kernel simply enables the high FP
> registers and continues the thread. For the most part the
> condition is harmless, but I've been looking at a panic
> that's the result of inconsistency in the high FP state,
> so the race is potentially fatal.
> 
> BTW: I never got the error when doing a buildworld. I
> think Anton's non-standard compiler options make GCC much
> more FP intensive and thus prone to causing the race.

Marcel, sorry, I probably misunderstood "compiler options"
in the previous reply. Did you mean -j option in
make -j10 buildworld? 

-- 
Anton Shterenlikht
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