On Wed, 2010-12-08 at 09:20 +0800, xufeng zhang wrote:

quoted

I believe it would have such an impact.  I don't see that user-mode
debugging would be enabled at all.

Maybe something like this untested patch:

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 84906d3..0e7d1cf 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c

@@ -323,6 +323,13 @@ static void set_debug_reg_defaults(struct thread_struct *thread)

  static void prime_debug_regs(struct thread_struct *thread)
  {
+	/*
+	 * If we're setting up debug events for user space, make sure they
+	 * don't fire in kernel space before we get to user space
+	 */
+	if (thread->dbcr0&  DBCR0_IDM)
+		mtmsr(mfmsr()&  ~MSR_DE);
+
  	mtspr(SPRN_IAC1, thread->iac1);
  	mtspr(SPRN_IAC2, thread->iac2);
  #if CONFIG_PPC_ADV_DEBUG_IACS>  2

   

Thanks for your reply, Dave, I know where the problem is.

So is there a kernel bug we need to fix ?

Cheers,
Ben.