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Message-ID: <20140502161939.26b61b7c@gandalf.local.home> Date: Fri, 2 May 2014 16:19:39 -0400 From: Steven Rostedt <rostedt@...dmis.org> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Andy Lutomirski <luto@...capital.net>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, "the arch/x86 maintainers" <x86@...nel.org>, "H. Peter Anvin" <h.peter.anvin@...el.com> Subject: Re: [RFC/HACK] x86: Fast return to kernel On Fri, 2 May 2014 12:31:42 -0700 Linus Torvalds <torvalds@...ux-foundation.org> wrote: > > And NMI not being re-enabled might just be a real advantage. Adding > Steven to the cc to make him aware of this patch. > There's not much of an advantage for NMIs, as they seldom page fault. We may get some due to vmalloc'd areas, but the whole nested NMI code that I wrote was to deal with breakpoints in NMIs. Although, this patch would have helped before my code, when doing things like dumping stacks from NMI context, as some stack dumps can trigger a page fault. In the past, I used dump all task's states from NMI context to find why the system locked up hard. But due to the re-enabling of NMIs with page faults, that usually caused the system to triple fault, and made that debugging method rather useless. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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