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ddb(4): improve wording

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Incorporate feedback overlooked in revew by wblock@

Sponsored by:		Netflix
Differential Revision:	https://reviews.freebsd.org/D4860
This commit is contained in:
Warner Losh 2021-07-12 15:13:13 -06:00
parent 71f6aea415
commit dc5a0d6d6d
1 changed files with 14 additions and 16 deletions
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30
share/man/man4/ddb.4
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@ -1538,41 +1538,39 @@ Embedded systems often use JTAG for debugging, but rarely use it in
combination with
.Nm .
.Pp
For serial consoles, you can enter the debugger by sending a BREAK
condition on the serial line if
Serial consoles can break to the debugger by sending a BREAK
condition on the serial line.
This requires a kernel built with
.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
special key sequence or menu selection.
Sending the break can be difficult or even happen spuriously in some setups.
An alternative method is to build a kernel with
.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-P causes a panic; 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.
In all these sequences, CR represents Carriage Return and is usually
sent by pressing 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
CTRL-x is Control x, send by pressing the Control key, then x, then releasing both.
and then releasing both.
.Pp
The break to enter the debugger behavior may be enabled at run-time
by setting the
The break-to-debugger behavior can be enabled by setting
.Xr sysctl 8
.Va debug.kdb.break_to_debugger
to 1.
The alternate sequence to enter the debugger behavior may be enabled
at run-time by setting the
The alt-break-to-debugger behavior can be enabled by setting
.Xr sysctl 8
.Va debug.kdb.alt_break_to_debugger
to 1.
The debugger may be entered by setting the
The debugger can be entered by setting
.Xr sysctl 8
.Va debug.kdb.enter
to 1.
.Pp
Output may be interrupted, paused, and resumed with the control
Output can be interrupted, paused, and resumed with the control
characters CTRL-C, CTRL-S, and CTRL-Q.
Because these control characters are received as in-band data from the
console, there is an input buffer, and once that buffer fills