lib/Kconfig.debug

   1
   2 config PRINTK_TIME
   3         bool "Show timing information on printks"
   4         depends on PRINTK
   5         help
   6           Selecting this option causes timing information to be
   7           included in printk output.  This allows you to measure
   8           the interval between kernel operations, including bootup
   9           operations.  This is useful for identifying long delays
  10           in kernel startup.
  11
  12 config ENABLE_WARN_DEPRECATED
  13         bool "Enable __deprecated logic"
  14         default y
  15         help
  16           Enable the __deprecated logic in the kernel build.
  17           Disable this to suppress the "warning: 'foo' is deprecated
  18           (declared at kernel/power/somefile.c:1234)" messages.
  19
  20 config ENABLE_MUST_CHECK
  21         bool "Enable __must_check logic"
  22         default y
  23         help
  24           Enable the __must_check logic in the kernel build.  Disable this to
  25           suppress the "warning: ignoring return value of 'foo', declared with
  26           attribute warn_unused_result" messages.
  27
  28 config FRAME_WARN
  29         int "Warn for stack frames larger than (needs gcc 4.4)"
  30         range 0 8192
  31         default 1024 if !64BIT
  32         default 2048 if 64BIT
  33         help
  34           Tell gcc to warn at build time for stack frames larger than this.
  35           Setting this too low will cause a lot of warnings.
  36           Setting it to 0 disables the warning.
  37           Requires gcc 4.4
  38
  39 config MAGIC_SYSRQ
  40         bool "Magic SysRq key"
  41         depends on !UML
  42         help
  43           If you say Y here, you will have some control over the system even
  44           if the system crashes for example during kernel debugging (e.g., you
  45           will be able to flush the buffer cache to disk, reboot the system
  46           immediately or dump some status information). This is accomplished
  47           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  48           also works on a serial console (on PC hardware at least), if you
  49           send a BREAK and then within 5 seconds a command keypress. The
  50           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  51           unless you really know what this hack does.
  52
  53 config UNUSED_SYMBOLS
  54         bool "Enable unused/obsolete exported symbols"
  55         default y if X86
  56         help
  57           Unused but exported symbols make the kernel needlessly bigger.  For
  58           that reason most of these unused exports will soon be removed.  This
  59           option is provided temporarily to provide a transition period in case
  60           some external kernel module needs one of these symbols anyway. If you
  61           encounter such a case in your module, consider if you are actually
  62           using the right API.  (rationale: since nobody in the kernel is using
  63           this in a module, there is a pretty good chance it's actually the
  64           wrong interface to use).  If you really need the symbol, please send a
  65           mail to the linux kernel mailing list mentioning the symbol and why
  66           you really need it, and what the merge plan to the mainline kernel for
  67           your module is.
  68
  69 config DEBUG_FS
  70         bool "Debug Filesystem"
  71         depends on SYSFS
  72         help
  73           debugfs is a virtual file system that kernel developers use to put
  74           debugging files into.  Enable this option to be able to read and
  75           write to these files.
  76
  77           If unsure, say N.
  78
  79 config HEADERS_CHECK
  80         bool "Run 'make headers_check' when building vmlinux"
  81         depends on !UML
  82         help
  83           This option will extract the user-visible kernel headers whenever
  84           building the kernel, and will run basic sanity checks on them to
  85           ensure that exported files do not attempt to include files which
  86           were not exported, etc.
  87
  88           If you're making modifications to header files which are
  89           relevant for userspace, say 'Y', and check the headers
  90           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  91           your build tree), to make sure they're suitable.
  92
  93 config DEBUG_SECTION_MISMATCH
  94         bool "Enable full Section mismatch analysis"
  95         depends on UNDEFINED
  96         # This option is on purpose disabled for now.
  97         # It will be enabled when we are down to a resonable number
  98         # of section mismatch warnings (< 10 for an allyesconfig build)
  99         help
 100           The section mismatch analysis checks if there are illegal
 101           references from one section to another section.
 102           Linux will during link or during runtime drop some sections
 103           and any use of code/data previously in these sections will
 104           most likely result in an oops.
 105           In the code functions and variables are annotated with
 106           __init, __devinit etc. (see full list in include/linux/init.h)
 107           which results in the code/data being placed in specific sections.
 108           The section mismatch analysis is always done after a full
 109           kernel build but enabling this option will in addition
 110           do the following:
 111           - Add the option -fno-inline-functions-called-once to gcc
 112             When inlining a function annotated __init in a non-init
 113             function we would lose the section information and thus
 114             the analysis would not catch the illegal reference.
 115             This option tells gcc to inline less but will also
 116             result in a larger kernel.
 117           - Run the section mismatch analysis for each module/built-in.o
 118             When we run the section mismatch analysis on vmlinux.o we
 119             lose valueble information about where the mismatch was
 120             introduced.
 121             Running the analysis for each module/built-in.o file
 122             will tell where the mismatch happens much closer to the
 123             source. The drawback is that we will report the same
 124             mismatch at least twice.
 125           - Enable verbose reporting from modpost to help solving
 126             the section mismatches reported.
 127
 128 config DEBUG_KERNEL
 129         bool "Kernel debugging"
 130         help
 131           Say Y here if you are developing drivers or trying to debug and
 132           identify kernel problems.
 133
 134 config DEBUG_SHIRQ
 135         bool "Debug shared IRQ handlers"
 136         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 137         help
 138           Enable this to generate a spurious interrupt as soon as a shared
 139           interrupt handler is registered, and just before one is deregistered.
 140           Drivers ought to be able to handle interrupts coming in at those
 141           points; some don't and need to be caught.
 142
 143 config DETECT_SOFTLOCKUP
 144         bool "Detect Soft Lockups"
 145         depends on DEBUG_KERNEL && !S390
 146         default y
 147         help
 148           Say Y here to enable the kernel to detect "soft lockups",
 149           which are bugs that cause the kernel to loop in kernel
 150           mode for more than 10 seconds, without giving other tasks a
 151           chance to run.
 152
 153           When a soft-lockup is detected, the kernel will print the
 154           current stack trace (which you should report), but the
 155           system will stay locked up. This feature has negligible
 156           overhead.
 157
 158           (Note that "hard lockups" are separate type of bugs that
 159            can be detected via the NMI-watchdog, on platforms that
 160            support it.)
 161
 162 config SCHED_DEBUG
 163         bool "Collect scheduler debugging info"
 164         depends on DEBUG_KERNEL && PROC_FS
 165         default y
 166         help
 167           If you say Y here, the /proc/sched_debug file will be provided
 168           that can help debug the scheduler. The runtime overhead of this
 169           option is minimal.
 170
 171 config SCHEDSTATS
 172         bool "Collect scheduler statistics"
 173         depends on DEBUG_KERNEL && PROC_FS
 174         help
 175           If you say Y here, additional code will be inserted into the
 176           scheduler and related routines to collect statistics about
 177           scheduler behavior and provide them in /proc/schedstat.  These
 178           stats may be useful for both tuning and debugging the scheduler
 179           If you aren't debugging the scheduler or trying to tune a specific
 180           application, you can say N to avoid the very slight overhead
 181           this adds.
 182
 183 config TIMER_STATS
 184         bool "Collect kernel timers statistics"
 185         depends on DEBUG_KERNEL && PROC_FS
 186         help
 187           If you say Y here, additional code will be inserted into the
 188           timer routines to collect statistics about kernel timers being
 189           reprogrammed. The statistics can be read from /proc/timer_stats.
 190           The statistics collection is started by writing 1 to /proc/timer_stats,
 191           writing 0 stops it. This feature is useful to collect information
 192           about timer usage patterns in kernel and userspace. This feature
 193           is lightweight if enabled in the kernel config but not activated
 194           (it defaults to deactivated on bootup and will only be activated
 195           if some application like powertop activates it explicitly).
 196
 197 config DEBUG_SLAB
 198         bool "Debug slab memory allocations"
 199         depends on DEBUG_KERNEL && SLAB
 200         help
 201           Say Y here to have the kernel do limited verification on memory
 202           allocation as well as poisoning memory on free to catch use of freed
 203           memory. This can make kmalloc/kfree-intensive workloads much slower.
 204
 205 config DEBUG_SLAB_LEAK
 206         bool "Memory leak debugging"
 207         depends on DEBUG_SLAB
 208
 209 config SLUB_DEBUG_ON
 210         bool "SLUB debugging on by default"
 211         depends on SLUB && SLUB_DEBUG
 212         default n
 213         help
 214           Boot with debugging on by default. SLUB boots by default with
 215           the runtime debug capabilities switched off. Enabling this is
 216           equivalent to specifying the "slub_debug" parameter on boot.
 217           There is no support for more fine grained debug control like
 218           possible with slub_debug=xxx. SLUB debugging may be switched
 219           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 220           "slub_debug=-".
 221
 222 config SLUB_STATS
 223         default n
 224         bool "Enable SLUB performance statistics"
 225         depends on SLUB && SLUB_DEBUG && SYSFS
 226         help
 227           SLUB statistics are useful to debug SLUBs allocation behavior in
 228           order find ways to optimize the allocator. This should never be
 229           enabled for production use since keeping statistics slows down
 230           the allocator by a few percentage points. The slabinfo command
 231           supports the determination of the most active slabs to figure
 232           out which slabs are relevant to a particular load.
 233           Try running: slabinfo -DA
 234
 235 config DEBUG_PREEMPT
 236         bool "Debug preemptible kernel"
 237         depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
 238         default y
 239         help
 240           If you say Y here then the kernel will use a debug variant of the
 241           commonly used smp_processor_id() function and will print warnings
 242           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 243           will detect preemption count underflows.
 244
 245 config DEBUG_RT_MUTEXES
 246         bool "RT Mutex debugging, deadlock detection"
 247         depends on DEBUG_KERNEL && RT_MUTEXES
 248         help
 249          This allows rt mutex semantics violations and rt mutex related
 250          deadlocks (lockups) to be detected and reported automatically.
 251
 252 config DEBUG_PI_LIST
 253         bool
 254         default y
 255         depends on DEBUG_RT_MUTEXES
 256
 257 config RT_MUTEX_TESTER
 258         bool "Built-in scriptable tester for rt-mutexes"
 259         depends on DEBUG_KERNEL && RT_MUTEXES
 260         help
 261           This option enables a rt-mutex tester.
 262
 263 config DEBUG_SPINLOCK
 264         bool "Spinlock and rw-lock debugging: basic checks"
 265         depends on DEBUG_KERNEL
 266         help
 267           Say Y here and build SMP to catch missing spinlock initialization
 268           and certain other kinds of spinlock errors commonly made.  This is
 269           best used in conjunction with the NMI watchdog so that spinlock
 270           deadlocks are also debuggable.
 271
 272 config DEBUG_MUTEXES
 273         bool "Mutex debugging: basic checks"
 274         depends on DEBUG_KERNEL
 275         help
 276          This feature allows mutex semantics violations to be detected and
 277          reported.
 278
 279 config DEBUG_LOCK_ALLOC
 280         bool "Lock debugging: detect incorrect freeing of live locks"
 281         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 282         select DEBUG_SPINLOCK
 283         select DEBUG_MUTEXES
 284         select LOCKDEP
 285         help
 286          This feature will check whether any held lock (spinlock, rwlock,
 287          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 288          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 289          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 290          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 291          held during task exit.
 292
 293 config PROVE_LOCKING
 294         bool "Lock debugging: prove locking correctness"
 295         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 296         select LOCKDEP
 297         select DEBUG_SPINLOCK
 298         select DEBUG_MUTEXES
 299         select DEBUG_LOCK_ALLOC
 300         default n
 301         help
 302          This feature enables the kernel to prove that all locking
 303          that occurs in the kernel runtime is mathematically
 304          correct: that under no circumstance could an arbitrary (and
 305          not yet triggered) combination of observed locking
 306          sequences (on an arbitrary number of CPUs, running an
 307          arbitrary number of tasks and interrupt contexts) cause a
 308          deadlock.
 309
 310          In short, this feature enables the kernel to report locking
 311          related deadlocks before they actually occur.
 312
 313          The proof does not depend on how hard and complex a
 314          deadlock scenario would be to trigger: how many
 315          participant CPUs, tasks and irq-contexts would be needed
 316          for it to trigger. The proof also does not depend on
 317          timing: if a race and a resulting deadlock is possible
 318          theoretically (no matter how unlikely the race scenario
 319          is), it will be proven so and will immediately be
 320          reported by the kernel (once the event is observed that
 321          makes the deadlock theoretically possible).
 322
 323          If a deadlock is impossible (i.e. the locking rules, as
 324          observed by the kernel, are mathematically correct), the
 325          kernel reports nothing.
 326
 327          NOTE: this feature can also be enabled for rwlocks, mutexes
 328          and rwsems - in which case all dependencies between these
 329          different locking variants are observed and mapped too, and
 330          the proof of observed correctness is also maintained for an
 331          arbitrary combination of these separate locking variants.
 332
 333          For more details, see Documentation/lockdep-design.txt.
 334
 335 config LOCKDEP
 336         bool
 337         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 338         select STACKTRACE
 339         select FRAME_POINTER if !X86 && !MIPS
 340         select KALLSYMS
 341         select KALLSYMS_ALL
 342
 343 config LOCK_STAT
 344         bool "Lock usage statistics"
 345         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 346         select LOCKDEP
 347         select DEBUG_SPINLOCK
 348         select DEBUG_MUTEXES
 349         select DEBUG_LOCK_ALLOC
 350         default n
 351         help
 352          This feature enables tracking lock contention points
 353
 354          For more details, see Documentation/lockstat.txt
 355
 356 config DEBUG_LOCKDEP
 357         bool "Lock dependency engine debugging"
 358         depends on DEBUG_KERNEL && LOCKDEP
 359         help
 360           If you say Y here, the lock dependency engine will do
 361           additional runtime checks to debug itself, at the price
 362           of more runtime overhead.
 363
 364 config TRACE_IRQFLAGS
 365         depends on DEBUG_KERNEL
 366         bool
 367         default y
 368         depends on TRACE_IRQFLAGS_SUPPORT
 369         depends on PROVE_LOCKING
 370
 371 config DEBUG_SPINLOCK_SLEEP
 372         bool "Spinlock debugging: sleep-inside-spinlock checking"
 373         depends on DEBUG_KERNEL
 374         help
 375           If you say Y here, various routines which may sleep will become very
 376           noisy if they are called with a spinlock held.
 377
 378 config DEBUG_LOCKING_API_SELFTESTS
 379         bool "Locking API boot-time self-tests"
 380         depends on DEBUG_KERNEL
 381         help
 382           Say Y here if you want the kernel to run a short self-test during
 383           bootup. The self-test checks whether common types of locking bugs
 384           are detected by debugging mechanisms or not. (if you disable
 385           lock debugging then those bugs wont be detected of course.)
 386           The following locking APIs are covered: spinlocks, rwlocks,
 387           mutexes and rwsems.
 388
 389 config STACKTRACE
 390         bool
 391         depends on DEBUG_KERNEL
 392         depends on STACKTRACE_SUPPORT
 393
 394 config DEBUG_KOBJECT
 395         bool "kobject debugging"
 396         depends on DEBUG_KERNEL
 397         help
 398           If you say Y here, some extra kobject debugging messages will be sent
 399           to the syslog.
 400
 401 config DEBUG_HIGHMEM
 402         bool "Highmem debugging"
 403         depends on DEBUG_KERNEL && HIGHMEM
 404         help
 405           This options enables addition error checking for high memory systems.
 406           Disable for production systems.
 407
 408 config DEBUG_BUGVERBOSE
 409         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 410         depends on BUG
 411         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 412                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 413         default !EMBEDDED
 414         help
 415           Say Y here to make BUG() panics output the file name and line number
 416           of the BUG call as well as the EIP and oops trace.  This aids
 417           debugging but costs about 70-100K of memory.
 418
 419 config DEBUG_INFO
 420         bool "Compile the kernel with debug info"
 421         depends on DEBUG_KERNEL
 422         help
 423           If you say Y here the resulting kernel image will include
 424           debugging info resulting in a larger kernel image.
 425           This adds debug symbols to the kernel and modules (gcc -g), and
 426           is needed if you intend to use kernel crashdump or binary object
 427           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 428           Say Y here only if you plan to debug the kernel.
 429
 430           If unsure, say N.
 431
 432 config DEBUG_VM
 433         bool "Debug VM"
 434         depends on DEBUG_KERNEL
 435         help
 436           Enable this to turn on extended checks in the virtual-memory system
 437           that may impact performance.
 438
 439           If unsure, say N.
 440
 441 config DEBUG_WRITECOUNT
 442         bool "Debug filesystem writers count"
 443         depends on DEBUG_KERNEL
 444         help
 445           Enable this to catch wrong use of the writers count in struct
 446           vfsmount.  This will increase the size of each file struct by
 447           32 bits.
 448
 449           If unsure, say N.
 450
 451 config DEBUG_LIST
 452         bool "Debug linked list manipulation"
 453         depends on DEBUG_KERNEL
 454         help
 455           Enable this to turn on extended checks in the linked-list
 456           walking routines.
 457
 458           If unsure, say N.
 459
 460 config DEBUG_SG
 461         bool "Debug SG table operations"
 462         depends on DEBUG_KERNEL
 463         help
 464           Enable this to turn on checks on scatter-gather tables. This can
 465           help find problems with drivers that do not properly initialize
 466           their sg tables.
 467
 468           If unsure, say N.
 469
 470 config FRAME_POINTER
 471         bool "Compile the kernel with frame pointers"
 472         depends on DEBUG_KERNEL && \
 473                 (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \
 474                  AVR32 || SUPERH || BLACKFIN || MN10300)
 475         default y if DEBUG_INFO && UML
 476         help
 477           If you say Y here the resulting kernel image will be slightly larger
 478           and slower, but it might give very useful debugging information on
 479           some architectures or if you use external debuggers.
 480           If you don't debug the kernel, you can say N.
 481
 482 config BOOT_PRINTK_DELAY
 483         bool "Delay each boot printk message by N milliseconds"
 484         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 485         help
 486           This build option allows you to read kernel boot messages
 487           by inserting a short delay after each one.  The delay is
 488           specified in milliseconds on the kernel command line,
 489           using "boot_delay=N".
 490
 491           It is likely that you would also need to use "lpj=M" to preset
 492           the "loops per jiffie" value.
 493           See a previous boot log for the "lpj" value to use for your
 494           system, and then set "lpj=M" before setting "boot_delay=N".
 495           NOTE:  Using this option may adversely affect SMP systems.
 496           I.e., processors other than the first one may not boot up.
 497           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 498           what it believes to be lockup conditions.
 499
 500 config RCU_TORTURE_TEST
 501         tristate "torture tests for RCU"
 502         depends on DEBUG_KERNEL
 503         depends on m
 504         default n
 505         help
 506           This option provides a kernel module that runs torture tests
 507           on the RCU infrastructure.  The kernel module may be built
 508           after the fact on the running kernel to be tested, if desired.
 509
 510           Say M if you want the RCU torture tests to build as a module.
 511           Say N if you are unsure.
 512
 513 config KPROBES_SANITY_TEST
 514         bool "Kprobes sanity tests"
 515         depends on DEBUG_KERNEL
 516         depends on KPROBES
 517         default n
 518         help
 519           This option provides for testing basic kprobes functionality on
 520           boot. A sample kprobe, jprobe and kretprobe are inserted and
 521           verified for functionality.
 522
 523           Say N if you are unsure.
 524
 525 config BACKTRACE_SELF_TEST
 526         tristate "Self test for the backtrace code"
 527         depends on DEBUG_KERNEL
 528         default n
 529         help
 530           This option provides a kernel module that can be used to test
 531           the kernel stack backtrace code. This option is not useful
 532           for distributions or general kernels, but only for kernel
 533           developers working on architecture code.
 534
 535           Say N if you are unsure.
 536
 537 config LKDTM
 538         tristate "Linux Kernel Dump Test Tool Module"
 539         depends on DEBUG_KERNEL
 540         depends on KPROBES
 541         depends on BLOCK
 542         default n
 543         help
 544         This module enables testing of the different dumping mechanisms by
 545         inducing system failures at predefined crash points.
 546         If you don't need it: say N
 547         Choose M here to compile this code as a module. The module will be
 548         called lkdtm.
 549
 550         Documentation on how to use the module can be found in
 551         drivers/misc/lkdtm.c
 552
 553 config FAULT_INJECTION
 554         bool "Fault-injection framework"
 555         depends on DEBUG_KERNEL
 556         help
 557           Provide fault-injection framework.
 558           For more details, see Documentation/fault-injection/.
 559
 560 config FAILSLAB
 561         bool "Fault-injection capability for kmalloc"
 562         depends on FAULT_INJECTION
 563         help
 564           Provide fault-injection capability for kmalloc.
 565
 566 config FAIL_PAGE_ALLOC
 567         bool "Fault-injection capabilitiy for alloc_pages()"
 568         depends on FAULT_INJECTION
 569         help
 570           Provide fault-injection capability for alloc_pages().
 571
 572 config FAIL_MAKE_REQUEST
 573         bool "Fault-injection capability for disk IO"
 574         depends on FAULT_INJECTION
 575         help
 576           Provide fault-injection capability for disk IO.
 577
 578 config FAULT_INJECTION_DEBUG_FS
 579         bool "Debugfs entries for fault-injection capabilities"
 580         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 581         help
 582           Enable configuration of fault-injection capabilities via debugfs.
 583
 584 config FAULT_INJECTION_STACKTRACE_FILTER
 585         bool "stacktrace filter for fault-injection capabilities"
 586         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 587         depends on !X86_64
 588         select STACKTRACE
 589         select FRAME_POINTER
 590         help
 591           Provide stacktrace filter for fault-injection capabilities
 592
 593 config LATENCYTOP
 594         bool "Latency measuring infrastructure"
 595         select FRAME_POINTER if !MIPS
 596         select KALLSYMS
 597         select KALLSYMS_ALL
 598         select STACKTRACE
 599         select SCHEDSTATS
 600         select SCHED_DEBUG
 601         depends on HAVE_LATENCYTOP_SUPPORT
 602         help
 603           Enable this option if you want to use the LatencyTOP tool
 604           to find out which userspace is blocking on what kernel operations.
 605
 606 config PROVIDE_OHCI1394_DMA_INIT
 607         bool "Remote debugging over FireWire early on boot"
 608         depends on PCI && X86
 609         help
 610           If you want to debug problems which hang or crash the kernel early
 611           on boot and the crashing machine has a FireWire port, you can use
 612           this feature to remotely access the memory of the crashed machine
 613           over FireWire. This employs remote DMA as part of the OHCI1394
 614           specification which is now the standard for FireWire controllers.
 615
 616           With remote DMA, you can monitor the printk buffer remotely using
 617           firescope and access all memory below 4GB using fireproxy from gdb.
 618           Even controlling a kernel debugger is possible using remote DMA.
 619
 620           Usage:
 621
 622           If ohci1394_dma=early is used as boot parameter, it will initialize
 623           all OHCI1394 controllers which are found in the PCI config space.
 624
 625           As all changes to the FireWire bus such as enabling and disabling
 626           devices cause a bus reset and thereby disable remote DMA for all
 627           devices, be sure to have the cable plugged and FireWire enabled on
 628           the debugging host before booting the debug target for debugging.
 629
 630           This code (~1k) is freed after boot. By then, the firewire stack
 631           in charge of the OHCI-1394 controllers should be used instead.
 632
 633           See Documentation/debugging-via-ohci1394.txt for more information.
 634
 635 config FIREWIRE_OHCI_REMOTE_DMA
 636         bool "Remote debugging over FireWire with firewire-ohci"
 637         depends on FIREWIRE_OHCI
 638         help
 639           This option lets you use the FireWire bus for remote debugging
 640           with help of the firewire-ohci driver. It enables unfiltered
 641           remote DMA in firewire-ohci.
 642           See Documentation/debugging-via-ohci1394.txt for more information.
 643
 644           If unsure, say N.
 645
 646 source "samples/Kconfig"
 647
 648 source "lib/Kconfig.kgdb"