Re: [Xenomai-help] fpu context switch issue

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Mark Saiia wrote:
> I applied the patch to Xenomai-2.4.5 with kernel 2.6.26.3 and observed the
> erroneous behavior.  I did the same with linux-2.6.27.5 and Xenomai r4372
> and noticed the same behavior.  Please let me know if I can run additional
> tests, if you need any more information, or how to potentially fix this
> issue.
> 
> Thank you,

Could you try the following patch ?

-- 
                                                 Gilles.

diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index f422387..f9f213a 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -1159,6 +1159,8 @@ asmlinkage void math_state_restore(void)
 	struct task_struct *tsk = thread->task;
 	unsigned long flags;

+ 	local_irq_save_hw_cond(flags);
+#ifndef CONFIG_IPIPE
 	if (!tsk_used_math(tsk)) {
 		local_irq_enable();
 		/*
@@ -1173,8 +1175,11 @@ asmlinkage void math_state_restore(void)
 		}
 		local_irq_disable();
 	}
-
- 	local_irq_save_hw_cond(flags);
+#else /* CONFIG_IPIPE */
+	if (!tsk_used_math(tsk))
+		/* No alloc, can not fail. */
+		init_fpu(tsk)
+#endif /* CONFIG_IPIPE */
 	clts();				/* Allow maths ops (or we recurse) */
 	restore_fpu(tsk);
 	thread->status |= TS_USEDFPU;	/* So we fnsave on switch_to() */