Messages in this thread | | | Subject | Re: [RFC][PATCH 5/5 v2] x86: Allow NMIs to hit breakpoints in i386 | From | Steven Rostedt <> | Date | Wed, 14 Dec 2011 14:33:15 -0500 |
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On Wed, 2011-12-14 at 10:26 -0800, H. Peter Anvin wrote: > On 12/13/2011 06:52 PM, Steven Rostedt wrote: > > With i386, NMIs and breakpoints use the current stack and they > > do not reset the stack pointer to a fix point that might corrupt > > a previous NMI or breakpoint (as it does in x86_64). But NMIs are > > still not made to be re-entrant, and need to prevent the case that > > an NMI hitting a breakpoint (which does an iret), doesn't allow > > another NMI to run. > > Okay... what about the other way around: avoiding the IRET when invoked > from an NMI context and therefore leaving NMI disabled until the > appropriate time?
Linus was against this approach. He didn't want the ugliness of NMI to spread to other code, by adding ugly handlers around the 'iret' of breakpoints and exceptions.
-- Steve
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