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author | imp <imp@FreeBSD.org> | 2016-01-14 16:23:07 +0000 |
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committer | imp <imp@FreeBSD.org> | 2016-01-14 16:23:07 +0000 |
commit | 94d0fcb350f3b75a5d24a16ee9801ed51c3db1b4 (patch) | |
tree | 014ebe883c0a3ca91085931fefc660e46b70b7ce /share/man/man4/ddb.4 | |
parent | b499f710a7abb9cb3b73b9f1cc071dba466386f2 (diff) | |
download | FreeBSD-src-94d0fcb350f3b75a5d24a16ee9801ed51c3db1b4.zip FreeBSD-src-94d0fcb350f3b75a5d24a16ee9801ed51c3db1b4.tar.gz |
Document how to enter the debugger here. I'm sure there's some better
canonical place, and the nit-pickers are welcome to move this
information there with a cross reference.
Differential Review: https://reviews.freebsd.org/D4860
Diffstat (limited to 'share/man/man4/ddb.4')
-rw-r--r-- | share/man/man4/ddb.4 | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/share/man/man4/ddb.4 b/share/man/man4/ddb.4 index d29bcdd..35b5dc1 100644 --- a/share/man/man4/ddb.4 +++ b/share/man/man4/ddb.4 @@ -1435,6 +1435,47 @@ 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 systems typically use IMPI to generate signals to enter the +debugger. +The +.Dv devel/ipmitool +port can be used to send the +.Cd chassis power diag +command which delivers an NMI to the processor. +.Pp +For serial consoles, you can break to the debugger by sending a BREAK +condition on the serial line if +.Cd options BREAK_TO_DEBUGGER +is specified in the kernel. +Most terminal emulation programs can send a break sequence with a +special key sequence or via a menu item. +However, in some setups, sending the break can be difficult to arrange +or happens spuriously, so if the kernel contains +.Cd options ALT_BREAK_TO_DEBUGGER +then the sequence of CR TILDE CTRL-B enters the debugger; +CR TILDE CTRL-P causes a panic instead of entering the +debugger; and +CR TILDE CTRL-R causes an immediate reboot. +In all the above sequences, CR is a Carriage Return and is usually +sent by hitting the Enter or Return key. +TILDE is the ASCII tilde character (~). +CTRL-x is Control x created by hitting the control key and then x +and then releasing both. +.Pp +The break to debugger behavior may also be enabled by setting the +.Xr sysctl 8 +.Dv debug.kdb.break_to_debugger +to 1. +The alt break to debugger behavior may also be enabled by setting the +.Xr sysctl 8 +.Dv debug.kdb.alt_break_to_debugger +to 1. +The debugger may be entered by setting the +.Xr sysctl 8 +.Dv debug.kdb.enter +to 1. .Sh FILES Header files mentioned in this manual page can be found below .Pa /usr/include |