lib/Kconfig.kgdb

   1 # SPDX-License-Identifier: GPL-2.0-only
   2
   3 config HAVE_ARCH_KGDB
   4         bool
   5
   6 # set if architecture has the its kgdb_arch_handle_qxfer_pkt
   7 # function to enable gdb stub to address XML packet sent from GDB.
   8 config HAVE_ARCH_KGDB_QXFER_PKT
   9         bool
  10
  11 menuconfig KGDB
  12         bool "KGDB: kernel debugger"
  13         depends on HAVE_ARCH_KGDB
  14         depends on DEBUG_KERNEL
  15         help
  16           If you say Y here, it will be possible to remotely debug the
  17           kernel using gdb.  It is recommended but not required, that
  18           you also turn on the kernel config option
  19           CONFIG_FRAME_POINTER to aid in producing more reliable stack
  20           backtraces in the external debugger.  Documentation of
  21           kernel debugger is available at http://kgdb.sourceforge.net
  22           as well as in Documentation/dev-tools/kgdb.rst.  If
  23           unsure, say N.
  24
  25 if KGDB
  26
  27 config KGDB_HONOUR_BLOCKLIST
  28         bool "KGDB: use kprobe blocklist to prohibit unsafe breakpoints"
  29         depends on HAVE_KPROBES
  30         depends on MODULES
  31         select KPROBES
  32         default y
  33         help
  34           If set to Y the debug core will use the kprobe blocklist to
  35           identify symbols where it is unsafe to set breakpoints.
  36           In particular this disallows instrumentation of functions
  37           called during debug trap handling and thus makes it very
  38           difficult to inadvertently provoke recursive trap handling.
  39
  40           If unsure, say Y.
  41
  42 config KGDB_SERIAL_CONSOLE
  43         tristate "KGDB: use kgdb over the serial console"
  44         select CONSOLE_POLL
  45         select MAGIC_SYSRQ
  46         depends on TTY && HW_CONSOLE
  47         default y
  48         help
  49           Share a serial console with kgdb. Sysrq-g must be used
  50           to break in initially.
  51
  52 config KGDB_TESTS
  53         bool "KGDB: internal test suite"
  54         default n
  55         help
  56           This is a kgdb I/O module specifically designed to test
  57           kgdb's internal functions.  This kgdb I/O module is
  58           intended to for the development of new kgdb stubs
  59           as well as regression testing the kgdb internals.
  60           See the drivers/misc/kgdbts.c for the details about
  61           the tests.  The most basic of this I/O module is to boot
  62           a kernel boot arguments "kgdbwait kgdbts=V1F100"
  63
  64 config KGDB_TESTS_ON_BOOT
  65         bool "KGDB: Run tests on boot"
  66         depends on KGDB_TESTS
  67         default n
  68         help
  69           Run the kgdb tests on boot up automatically without the need
  70           to pass in a kernel parameter
  71
  72 config KGDB_TESTS_BOOT_STRING
  73         string "KGDB: which internal kgdb tests to run"
  74         depends on KGDB_TESTS_ON_BOOT
  75         default "V1F100"
  76         help
  77           This is the command string to send the kgdb test suite on
  78           boot.  See the drivers/misc/kgdbts.c for detailed
  79           information about other strings you could use beyond the
  80           default of V1F100.
  81
  82 config KGDB_LOW_LEVEL_TRAP
  83        bool "KGDB: Allow debugging with traps in notifiers"
  84        depends on X86 || MIPS
  85        default n
  86        help
  87          This will add an extra call back to kgdb for the breakpoint
  88          exception handler which will allow kgdb to step through a
  89          notify handler.
  90
  91 config KGDB_KDB
  92         bool "KGDB_KDB: include kdb frontend for kgdb"
  93         default n
  94         help
  95           KDB frontend for kernel
  96
  97 config KDB_DEFAULT_ENABLE
  98         hex "KDB: Select kdb command functions to be enabled by default"
  99         depends on KGDB_KDB
 100         default 0x1
 101         help
 102           Specifiers which kdb commands are enabled by default. This may
 103           be set to 1 or 0 to enable all commands or disable almost all
 104           commands.
 105
 106           Alternatively the following bitmask applies:
 107
 108             0x0002 - allow arbitrary reads from memory and symbol lookup
 109             0x0004 - allow arbitrary writes to memory
 110             0x0008 - allow current register state to be inspected
 111             0x0010 - allow current register state to be modified
 112             0x0020 - allow passive inspection (backtrace, process list, lsmod)
 113             0x0040 - allow flow control management (breakpoint, single step)
 114             0x0080 - enable signalling of processes
 115             0x0100 - allow machine to be rebooted
 116
 117           The config option merely sets the default at boot time. Both
 118           issuing 'echo X > /sys/module/kdb/parameters/cmd_enable' or
 119           setting with kdb.cmd_enable=X kernel command line option will
 120           override the default settings.
 121
 122 config KDB_KEYBOARD
 123         bool "KGDB_KDB: keyboard as input device"
 124         depends on VT && KGDB_KDB && !PARISC
 125         default n
 126         help
 127           KDB can use a PS/2 type keyboard for an input device
 128
 129 config KDB_CONTINUE_CATASTROPHIC
 130         int "KDB: continue after catastrophic errors"
 131         depends on KGDB_KDB
 132         default "0"
 133         help
 134           This integer controls the behaviour of kdb when the kernel gets a
 135           catastrophic error, i.e. for a panic or oops.
 136           When KDB is active and a catastrophic error occurs, nothing extra
 137           will happen until you type 'go'.
 138           CONFIG_KDB_CONTINUE_CATASTROPHIC == 0 (default). The first time
 139           you type 'go', you will be warned by kdb. The secend time you type
 140           'go', KDB tries to continue. No guarantees that the
 141           kernel is still usable in this situation.
 142           CONFIG_KDB_CONTINUE_CATASTROPHIC == 1. KDB tries to continue.
 143           No guarantees that the kernel is still usable in this situation.
 144           CONFIG_KDB_CONTINUE_CATASTROPHIC == 2. KDB forces a reboot.
 145           If you are not sure, say 0.
 146
 147 config ARCH_HAS_EARLY_DEBUG
 148         bool
 149         default n
 150         help
 151           If an architecture can definitely handle entering the debugger
 152           when early_param's are parsed then it select this config.
 153           Otherwise, if "kgdbwait" is passed on the kernel command line it
 154           won't actually be processed until dbg_late_init() just after the
 155           call to kgdb_arch_late() is made.
 156
 157           NOTE: Even if this isn't selected by an architecture we will
 158           still try to register kgdb to handle breakpoints and crashes
 159           when early_param's are parsed, we just won't act on the
 160           "kgdbwait" parameter until dbg_late_init().  If you get a
 161           crash and try to drop into kgdb somewhere between these two
 162           places you might or might not end up being able to use kgdb
 163           depending on exactly how far along the architecture has initted.
 164
 165 endif # KGDB