Date: Fri, 30 Nov 2018 15:52:04 +0000 (UTC) From: Edward Tomasz Napierala <trasz@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r341342 - head/share/man/man4 Message-ID: <201811301552.wAUFq40O058961@repo.freebsd.org>
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Author: trasz Date: Fri Nov 30 15:52:03 2018 New Revision: 341342 URL: https://svnweb.freebsd.org/changeset/base/341342 Log: Revert r341337; according to imp@ we still support these. MFC after: 2 weeks Sponsored by: DARPA, AFRL Modified: head/share/man/man4/ddb.4 Modified: head/share/man/man4/ddb.4 ============================================================================== --- head/share/man/man4/ddb.4 Fri Nov 30 12:17:35 2018 (r341341) +++ head/share/man/man4/ddb.4 Fri Nov 30 15:52:03 2018 (r341342) @@ -1491,8 +1491,17 @@ might be defined to have special handling, and might be defined to simply panic and reboot. .El .Sh HINTS +On machines with an ISA expansion bus, a simple NMI generation card can be +constructed by connecting a push button between the A01 and B01 (CHCHK# and +GND) card fingers. +Momentarily shorting these two fingers together may cause the bridge chipset to +generate an NMI, which causes the kernel to pass control to +.Nm . +Some bridge chipsets do not generate a NMI on CHCHK#, so your mileage may vary. The NMI allows one to break into the debugger on a wedged machine to diagnose problems. +Other bus' bridge chipsets may be able to generate NMI using bus specific +methods. There are many PCI and PCIe add-in cards which can generate NMI for debugging. Modern server systems typically use IPMI to generate signals to enter the
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