NAME
cn_init_magic
,
cn_trap
, cn_isconsole
,
cn_check_magic
,
cn_destroy_magic
,
cn_set_magic
, cn_get_magic
— console magic key sequence
management
SYNOPSIS
#include
<sys/systm.h>
void
cn_init_magic
(cnm_state_t
*cnms);
void
cn_trap
();
int
cn_isconsole
(dev_t
dev);
void
cn_check_magic
(dev_t
dev, int k,
cnm_state_t *cnms);
void
cn_destroy_magic
(cnm_state_t
*cnms);
int
cn_set_magic
(char
*magic);
int
cn_get_magic
(char
*magic, int
len);
DESCRIPTION
The NetBSD console magic key sequence management framework is designed to provide flexible methods to set, change, and detect magic key sequences on console devices and break into the debugger or ROM monitor with a minimum of interrupt latency.Drivers that generate console input should make
use of these routines. A different cnm_state_t should
be used for each separate input stream. Multiple devices that share the same
input stream, such as USB keyboards, can share the same
cnm_state_t. Once a cnm_state_t
is allocated, it should be initialized with
cn_init_magic
()
so it can be used by
cn_check_magic
().
If a driver thinks it might be the console input device it can set the magic
sequence with cn_set_magic
() to any arbitrary
string. Whenever the driver receives input, it should call
cn_check_magic
() to process the data and determine
whether the magic sequence has been hit.
The magic key sequence can be accessed through the
hw.cnmagic sysctl
variable.
This is the raw data and may be keycodes rather than processed characters,
depending on the console device.
FUNCTIONS
The following functions describe the console magic interface.
cn_init_magic
(cnm)- Initialize the console magic state pointed to by cnm to a usable state.
cn_trap
()- Trap into the kernel debugger or ROM monitor. By default this routine is
defined to be
console_debugger
() but can be overridden in MI header files. cn_isconsole
(dev)- Determine whether a given dev is the system console. This macro tests to see if dev is the same as cn_tab->cn_dev but can be overridden in MI header files.
cn_check_magic
(dev, k, cnms)- All input should be passed through
cn_check_magic
() so the state machine remains in a consistent state.cn_check_magic
() callscn_isconsole
() with dev to determine if this is the console. If that returns true then it runs the input value k through the state machine. If the state machine completes a match of the current console magic sequencecn_trap
() is called. Some input may need to be translated to state machine values such as the serial lineBREAK
sequence. cn_destroy_magic
(cnms)- This should be called once what cnms points to is no longer needed.
cn_set_magic
(magic)cn_set_magic
() encodes anul
terminated arbitrary string into values that can be used by the state machine and installs it as the global magic sequence. The escape sequence is character value0x27
and can be used to encode special values:- 0x27
- The literal value
0x27
. - 0x01
- Serial
BREAK
sequence. - 0x02
Nul
character.
Returns
0
on success or a non-zero error value.cn_get_magic
(magic, len)- Extract the current magic sequence from the state machine and return up to
len bytes of it in the buffer pointed to by
magic. It uses the same encoding accepted by
cn_set_magic
(). Returns0
on success or a non-zero error value.
SEE ALSO
HISTORY
The NetBSD console magic key sequence management framework first appeared in NetBSD 1.6.
AUTHORS
The NetBSD console magic key sequence management framework was designed and implemented by Eduardo Horvath ⟨eeh@NetBSD.org⟩.