On Thu, Jan 23, 2025 at 09:15:09AM -0800, Josh Poimboeuf wrote: > On Thu, Jan 23, 2025 at 09:14:03AM +0100, Peter Zijlstra wrote: > > On Wed, Jan 22, 2025 at 12:47:20PM -0800, Josh Poimboeuf wrote: > > > What exactly do you mean by "NMI like"? Is it because a #DB might be > > > basically running in NMI context, if the NMI hit a breakpoint? > > > > No, #DB, #BP and such are considered NMI (and will have in_nmi() true) > > because they can trigger anywhere, including sections where IRQs are > > disabled. > > So: > > - while exceptions are technically not NMI, they're "NMI" because they > can occur in NMI or IRQ-disabled regions > > - such "NMI" exceptions can be preempted by NMIs and "NMIs" > > - NMIs can be preempted by "NMIs" but not NMIs (except in entry code!) > > ... did I get all that right? Not subtle at all!
Yeah, sounds about right :-)
