1menu "Kernel hacking"
  2
  3config TRACE_IRQFLAGS_SUPPORT
  4	def_bool y
  5
  6source "lib/Kconfig.debug"
  7
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  8config X86_VERBOSE_BOOTUP
  9	bool "Enable verbose x86 bootup info messages"
 10	default y
 11	---help---
 12	  Enables the informational output from the decompression stage
 13	  (e.g. bzImage) of the boot. If you disable this you will still
 14	  see errors. Disable this if you want silent bootup.
 15
 16config EARLY_PRINTK
 17	bool "Early printk" if EXPERT
 18	default y
 19	---help---
 20	  Write kernel log output directly into the VGA buffer or to a serial
 21	  port.
 22
 23	  This is useful for kernel debugging when your machine crashes very
 24	  early before the console code is initialized. For normal operation
 25	  it is not recommended because it looks ugly and doesn't cooperate
 26	  with klogd/syslogd or the X server. You should normally N here,
 27	  unless you want to debug such a crash.
 28
 
 
 
 
 29config EARLY_PRINTK_DBGP
 30	bool "Early printk via EHCI debug port"
 31	depends on EARLY_PRINTK && PCI
 32	---help---
 33	  Write kernel log output directly into the EHCI debug port.
 34
 35	  This is useful for kernel debugging when your machine crashes very
 36	  early before the console code is initialized. For normal operation
 37	  it is not recommended because it looks ugly and doesn't cooperate
 38	  with klogd/syslogd or the X server. You should normally N here,
 39	  unless you want to debug such a crash. You need usb debug device.
 40
 41config EARLY_PRINTK_EFI
 42	bool "Early printk via the EFI framebuffer"
 43	depends on EFI && EARLY_PRINTK
 44	select FONT_SUPPORT
 45	---help---
 46	  Write kernel log output directly into the EFI framebuffer.
 47
 48	  This is useful for kernel debugging when your machine crashes very
 49	  early before the console code is initialized.
 50
 51config X86_PTDUMP_CORE
 52	def_bool n
 53
 54config X86_PTDUMP
 55	tristate "Export kernel pagetable layout to userspace via debugfs"
 56	depends on DEBUG_KERNEL
 57	select DEBUG_FS
 58	select X86_PTDUMP_CORE
 59	---help---
 60	  Say Y here if you want to show the kernel pagetable layout in a
 61	  debugfs file. This information is only useful for kernel developers
 62	  who are working in architecture specific areas of the kernel.
 63	  It is probably not a good idea to enable this feature in a production
 64	  kernel.
 65	  If in doubt, say "N"
 66
 67config EFI_PGT_DUMP
 68	bool "Dump the EFI pagetable"
 69	depends on EFI
 70	select X86_PTDUMP_CORE
 71	---help---
 72	  Enable this if you want to dump the EFI page table before
 73	  enabling virtual mode. This can be used to debug miscellaneous
 74	  issues with the mapping of the EFI runtime regions into that
 75	  table.
 76
 77config DEBUG_RODATA_TEST
 78	bool "Testcase for the marking rodata read-only"
 
 79	default y
 80	---help---
 81	  This option enables a testcase for the setting rodata read-only
 82	  as well as for the change_page_attr() infrastructure.
 83	  If in doubt, say "N"
 84
 85config DEBUG_WX
 86	bool "Warn on W+X mappings at boot"
 87	select X86_PTDUMP_CORE
 88	---help---
 89	  Generate a warning if any W+X mappings are found at boot.
 90
 91	  This is useful for discovering cases where the kernel is leaving
 92	  W+X mappings after applying NX, as such mappings are a security risk.
 93
 94	  Look for a message in dmesg output like this:
 95
 96	    x86/mm: Checked W+X mappings: passed, no W+X pages found.
 97
 98	  or like this, if the check failed:
 99
100	    x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
101
102	  Note that even if the check fails, your kernel is possibly
103	  still fine, as W+X mappings are not a security hole in
104	  themselves, what they do is that they make the exploitation
105	  of other unfixed kernel bugs easier.
106
107	  There is no runtime or memory usage effect of this option
108	  once the kernel has booted up - it's a one time check.
109
110	  If in doubt, say "Y".
111
112config DEBUG_SET_MODULE_RONX
113	bool "Set loadable kernel module data as NX and text as RO"
114	depends on MODULES
115	---help---
116	  This option helps catch unintended modifications to loadable
117	  kernel module's text and read-only data. It also prevents execution
118	  of module data. Such protection may interfere with run-time code
119	  patching and dynamic kernel tracing - and they might also protect
120	  against certain classes of kernel exploits.
121	  If in doubt, say "N".
122
123config DEBUG_NX_TEST
124	tristate "Testcase for the NX non-executable stack feature"
125	depends on DEBUG_KERNEL && m
126	---help---
127	  This option enables a testcase for the CPU NX capability
128	  and the software setup of this feature.
129	  If in doubt, say "N"
130
131config DOUBLEFAULT
132	default y
133	bool "Enable doublefault exception handler" if EXPERT
 
134	---help---
135	  This option allows trapping of rare doublefault exceptions that
136	  would otherwise cause a system to silently reboot. Disabling this
137	  option saves about 4k and might cause you much additional grey
138	  hair.
139
140config DEBUG_TLBFLUSH
141	bool "Set upper limit of TLB entries to flush one-by-one"
142	depends on DEBUG_KERNEL
143	---help---
144
145	X86-only for now.
146
147	This option allows the user to tune the amount of TLB entries the
148	kernel flushes one-by-one instead of doing a full TLB flush. In
149	certain situations, the former is cheaper. This is controlled by the
150	tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
151	to -1, the code flushes the whole TLB unconditionally. Otherwise,
152	for positive values of it, the kernel will use single TLB entry
153	invalidating instructions according to the following formula:
154
155	flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
156
157	If in doubt, say "N".
158
159config IOMMU_DEBUG
160	bool "Enable IOMMU debugging"
161	depends on GART_IOMMU && DEBUG_KERNEL
162	depends on X86_64
163	---help---
164	  Force the IOMMU to on even when you have less than 4GB of
165	  memory and add debugging code. On overflow always panic. And
166	  allow to enable IOMMU leak tracing. Can be disabled at boot
167	  time with iommu=noforce. This will also enable scatter gather
168	  list merging.  Currently not recommended for production
169	  code. When you use it make sure you have a big enough
170	  IOMMU/AGP aperture.  Most of the options enabled by this can
171	  be set more finegrained using the iommu= command line
172	  options. See Documentation/x86/x86_64/boot-options.txt for more
173	  details.
174
175config IOMMU_STRESS
176	bool "Enable IOMMU stress-test mode"
177	---help---
178	  This option disables various optimizations in IOMMU related
179	  code to do real stress testing of the IOMMU code. This option
180	  will cause a performance drop and should only be enabled for
181	  testing.
182
183config IOMMU_LEAK
184	bool "IOMMU leak tracing"
185	depends on IOMMU_DEBUG && DMA_API_DEBUG
186	---help---
187	  Add a simple leak tracer to the IOMMU code. This is useful when you
188	  are debugging a buggy device driver that leaks IOMMU mappings.
189
190config HAVE_MMIOTRACE_SUPPORT
191	def_bool y
192
193config X86_DECODER_SELFTEST
194	bool "x86 instruction decoder selftest"
195	depends on DEBUG_KERNEL && KPROBES
196	depends on !COMPILE_TEST
197	---help---
198	 Perform x86 instruction decoder selftests at build time.
199	 This option is useful for checking the sanity of x86 instruction
200	 decoder code.
201	 If unsure, say "N".
202
203#
204# IO delay types:
205#
206
207config IO_DELAY_TYPE_0X80
208	int
209	default "0"
210
211config IO_DELAY_TYPE_0XED
212	int
213	default "1"
214
215config IO_DELAY_TYPE_UDELAY
216	int
217	default "2"
218
219config IO_DELAY_TYPE_NONE
220	int
221	default "3"
222
223choice
224	prompt "IO delay type"
225	default IO_DELAY_0X80
226
227config IO_DELAY_0X80
228	bool "port 0x80 based port-IO delay [recommended]"
229	---help---
230	  This is the traditional Linux IO delay used for in/out_p.
231	  It is the most tested hence safest selection here.
232
233config IO_DELAY_0XED
234	bool "port 0xed based port-IO delay"
235	---help---
236	  Use port 0xed as the IO delay. This frees up port 0x80 which is
237	  often used as a hardware-debug port.
238
239config IO_DELAY_UDELAY
240	bool "udelay based port-IO delay"
241	---help---
242	  Use udelay(2) as the IO delay method. This provides the delay
243	  while not having any side-effect on the IO port space.
244
245config IO_DELAY_NONE
246	bool "no port-IO delay"
247	---help---
248	  No port-IO delay. Will break on old boxes that require port-IO
249	  delay for certain operations. Should work on most new machines.
250
251endchoice
252
253if IO_DELAY_0X80
254config DEFAULT_IO_DELAY_TYPE
255	int
256	default IO_DELAY_TYPE_0X80
257endif
258
259if IO_DELAY_0XED
260config DEFAULT_IO_DELAY_TYPE
261	int
262	default IO_DELAY_TYPE_0XED
263endif
264
265if IO_DELAY_UDELAY
266config DEFAULT_IO_DELAY_TYPE
267	int
268	default IO_DELAY_TYPE_UDELAY
269endif
270
271if IO_DELAY_NONE
272config DEFAULT_IO_DELAY_TYPE
273	int
274	default IO_DELAY_TYPE_NONE
275endif
276
277config DEBUG_BOOT_PARAMS
278	bool "Debug boot parameters"
279	depends on DEBUG_KERNEL
280	depends on DEBUG_FS
281	---help---
282	  This option will cause struct boot_params to be exported via debugfs.
283
284config CPA_DEBUG
285	bool "CPA self-test code"
286	depends on DEBUG_KERNEL
287	---help---
288	  Do change_page_attr() self-tests every 30 seconds.
289
290config OPTIMIZE_INLINING
291	bool "Allow gcc to uninline functions marked 'inline'"
292	---help---
293	  This option determines if the kernel forces gcc to inline the functions
294	  developers have marked 'inline'. Doing so takes away freedom from gcc to
295	  do what it thinks is best, which is desirable for the gcc 3.x series of
296	  compilers. The gcc 4.x series have a rewritten inlining algorithm and
297	  enabling this option will generate a smaller kernel there. Hopefully
298	  this algorithm is so good that allowing gcc 4.x and above to make the
299	  decision will become the default in the future. Until then this option
300	  is there to test gcc for this.
301
302	  If unsure, say N.
303
304config DEBUG_ENTRY
305	bool "Debug low-level entry code"
306	depends on DEBUG_KERNEL
307	---help---
308	  This option enables sanity checks in x86's low-level entry code.
309	  Some of these sanity checks may slow down kernel entries and
310	  exits or otherwise impact performance.
311
312	  This is currently used to help test NMI code.
 
 
313
314	  If unsure, say N.
315
316config DEBUG_NMI_SELFTEST
317	bool "NMI Selftest"
318	depends on DEBUG_KERNEL && X86_LOCAL_APIC
319	---help---
320	  Enabling this option turns on a quick NMI selftest to verify
321	  that the NMI behaves correctly.
322
323	  This might help diagnose strange hangs that rely on NMI to
324	  function properly.
325
326	  If unsure, say N.
327
328config DEBUG_IMR_SELFTEST
329	bool "Isolated Memory Region self test"
330	default n
331	depends on INTEL_IMR
332	---help---
333	  This option enables automated sanity testing of the IMR code.
334	  Some simple tests are run to verify IMR bounds checking, alignment
335	  and overlapping. This option is really only useful if you are
336	  debugging an IMR memory map or are modifying the IMR code and want to
337	  test your changes.
338
339	  If unsure say N here.
340
341config X86_DEBUG_FPU
342	bool "Debug the x86 FPU code"
343	depends on DEBUG_KERNEL
344	default y
345	---help---
346	  If this option is enabled then there will be extra sanity
347	  checks and (boot time) debug printouts added to the kernel.
348	  This debugging adds some small amount of runtime overhead
349	  to the kernel.
350
351	  If unsure, say N.
352
353config PUNIT_ATOM_DEBUG
354	tristate "ATOM Punit debug driver"
355	select DEBUG_FS
356	select IOSF_MBI
357	---help---
358	  This is a debug driver, which gets the power states
359	  of all Punit North Complex devices. The power states of
360	  each device is exposed as part of the debugfs interface.
361	  The current power state can be read from
362	  /sys/kernel/debug/punit_atom/dev_power_state
363
364endmenu

  1menu "Kernel hacking"
  2
  3config TRACE_IRQFLAGS_SUPPORT
  4	def_bool y
  5
  6source "lib/Kconfig.debug"
  7
  8config STRICT_DEVMEM
  9	bool "Filter access to /dev/mem"
 10	---help---
 11	  If this option is disabled, you allow userspace (root) access to all
 12	  of memory, including kernel and userspace memory. Accidental
 13	  access to this is obviously disastrous, but specific access can
 14	  be used by people debugging the kernel. Note that with PAT support
 15	  enabled, even in this case there are restrictions on /dev/mem
 16	  use due to the cache aliasing requirements.
 17
 18	  If this option is switched on, the /dev/mem file only allows
 19	  userspace access to PCI space and the BIOS code and data regions.
 20	  This is sufficient for dosemu and X and all common users of
 21	  /dev/mem.
 22
 23	  If in doubt, say Y.
 24
 25config X86_VERBOSE_BOOTUP
 26	bool "Enable verbose x86 bootup info messages"
 27	default y
 28	---help---
 29	  Enables the informational output from the decompression stage
 30	  (e.g. bzImage) of the boot. If you disable this you will still
 31	  see errors. Disable this if you want silent bootup.
 32
 33config EARLY_PRINTK
 34	bool "Early printk" if EXPERT
 35	default y
 36	---help---
 37	  Write kernel log output directly into the VGA buffer or to a serial
 38	  port.
 39
 40	  This is useful for kernel debugging when your machine crashes very
 41	  early before the console code is initialized. For normal operation
 42	  it is not recommended because it looks ugly and doesn't cooperate
 43	  with klogd/syslogd or the X server. You should normally N here,
 44	  unless you want to debug such a crash.
 45
 46config EARLY_PRINTK_INTEL_MID
 47	bool "Early printk for Intel MID platform support"
 48	depends on EARLY_PRINTK && X86_INTEL_MID
 49
 50config EARLY_PRINTK_DBGP
 51	bool "Early printk via EHCI debug port"
 52	depends on EARLY_PRINTK && PCI
 53	---help---
 54	  Write kernel log output directly into the EHCI debug port.
 55
 56	  This is useful for kernel debugging when your machine crashes very
 57	  early before the console code is initialized. For normal operation
 58	  it is not recommended because it looks ugly and doesn't cooperate
 59	  with klogd/syslogd or the X server. You should normally N here,
 60	  unless you want to debug such a crash. You need usb debug device.
 61
 62config DEBUG_STACKOVERFLOW
 63	bool "Check for stack overflows"
 64	depends on DEBUG_KERNEL
 
 65	---help---
 66	  Say Y here if you want to check the overflows of kernel, IRQ
 67	  and exception stacks. This option will cause messages of the
 68	  stacks in detail when free stack space drops below a certain
 69	  limit.
 70	  If in doubt, say "N".
 
 
 71
 72config X86_PTDUMP
 73	bool "Export kernel pagetable layout to userspace via debugfs"
 74	depends on DEBUG_KERNEL
 75	select DEBUG_FS
 
 76	---help---
 77	  Say Y here if you want to show the kernel pagetable layout in a
 78	  debugfs file. This information is only useful for kernel developers
 79	  who are working in architecture specific areas of the kernel.
 80	  It is probably not a good idea to enable this feature in a production
 81	  kernel.
 82	  If in doubt, say "N"
 83
 84config DEBUG_RODATA
 85	bool "Write protect kernel read-only data structures"
 86	default y
 87	depends on DEBUG_KERNEL
 88	---help---
 89	  Mark the kernel read-only data as write-protected in the pagetables,
 90	  in order to catch accidental (and incorrect) writes to such const
 91	  data. This is recommended so that we can catch kernel bugs sooner.
 92	  If in doubt, say "Y".
 93
 94config DEBUG_RODATA_TEST
 95	bool "Testcase for the DEBUG_RODATA feature"
 96	depends on DEBUG_RODATA
 97	default y
 98	---help---
 99	  This option enables a testcase for the DEBUG_RODATA
100	  feature as well as for the change_page_attr() infrastructure.
101	  If in doubt, say "N"
102
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
103config DEBUG_SET_MODULE_RONX
104	bool "Set loadable kernel module data as NX and text as RO"
105	depends on MODULES
106	---help---
107	  This option helps catch unintended modifications to loadable
108	  kernel module's text and read-only data. It also prevents execution
109	  of module data. Such protection may interfere with run-time code
110	  patching and dynamic kernel tracing - and they might also protect
111	  against certain classes of kernel exploits.
112	  If in doubt, say "N".
113
114config DEBUG_NX_TEST
115	tristate "Testcase for the NX non-executable stack feature"
116	depends on DEBUG_KERNEL && m
117	---help---
118	  This option enables a testcase for the CPU NX capability
119	  and the software setup of this feature.
120	  If in doubt, say "N"
121
122config DOUBLEFAULT
123	default y
124	bool "Enable doublefault exception handler" if EXPERT
125	depends on X86_32
126	---help---
127	  This option allows trapping of rare doublefault exceptions that
128	  would otherwise cause a system to silently reboot. Disabling this
129	  option saves about 4k and might cause you much additional grey
130	  hair.
131
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
132config IOMMU_DEBUG
133	bool "Enable IOMMU debugging"
134	depends on GART_IOMMU && DEBUG_KERNEL
135	depends on X86_64
136	---help---
137	  Force the IOMMU to on even when you have less than 4GB of
138	  memory and add debugging code. On overflow always panic. And
139	  allow to enable IOMMU leak tracing. Can be disabled at boot
140	  time with iommu=noforce. This will also enable scatter gather
141	  list merging.  Currently not recommended for production
142	  code. When you use it make sure you have a big enough
143	  IOMMU/AGP aperture.  Most of the options enabled by this can
144	  be set more finegrained using the iommu= command line
145	  options. See Documentation/x86/x86_64/boot-options.txt for more
146	  details.
147
148config IOMMU_STRESS
149	bool "Enable IOMMU stress-test mode"
150	---help---
151	  This option disables various optimizations in IOMMU related
152	  code to do real stress testing of the IOMMU code. This option
153	  will cause a performance drop and should only be enabled for
154	  testing.
155
156config IOMMU_LEAK
157	bool "IOMMU leak tracing"
158	depends on IOMMU_DEBUG && DMA_API_DEBUG
159	---help---
160	  Add a simple leak tracer to the IOMMU code. This is useful when you
161	  are debugging a buggy device driver that leaks IOMMU mappings.
162
163config HAVE_MMIOTRACE_SUPPORT
164	def_bool y
165
166config X86_DECODER_SELFTEST
167	bool "x86 instruction decoder selftest"
168	depends on DEBUG_KERNEL && KPROBES
 
169	---help---
170	 Perform x86 instruction decoder selftests at build time.
171	 This option is useful for checking the sanity of x86 instruction
172	 decoder code.
173	 If unsure, say "N".
174
175#
176# IO delay types:
177#
178
179config IO_DELAY_TYPE_0X80
180	int
181	default "0"
182
183config IO_DELAY_TYPE_0XED
184	int
185	default "1"
186
187config IO_DELAY_TYPE_UDELAY
188	int
189	default "2"
190
191config IO_DELAY_TYPE_NONE
192	int
193	default "3"
194
195choice
196	prompt "IO delay type"
197	default IO_DELAY_0X80
198
199config IO_DELAY_0X80
200	bool "port 0x80 based port-IO delay [recommended]"
201	---help---
202	  This is the traditional Linux IO delay used for in/out_p.
203	  It is the most tested hence safest selection here.
204
205config IO_DELAY_0XED
206	bool "port 0xed based port-IO delay"
207	---help---
208	  Use port 0xed as the IO delay. This frees up port 0x80 which is
209	  often used as a hardware-debug port.
210
211config IO_DELAY_UDELAY
212	bool "udelay based port-IO delay"
213	---help---
214	  Use udelay(2) as the IO delay method. This provides the delay
215	  while not having any side-effect on the IO port space.
216
217config IO_DELAY_NONE
218	bool "no port-IO delay"
219	---help---
220	  No port-IO delay. Will break on old boxes that require port-IO
221	  delay for certain operations. Should work on most new machines.
222
223endchoice
224
225if IO_DELAY_0X80
226config DEFAULT_IO_DELAY_TYPE
227	int
228	default IO_DELAY_TYPE_0X80
229endif
230
231if IO_DELAY_0XED
232config DEFAULT_IO_DELAY_TYPE
233	int
234	default IO_DELAY_TYPE_0XED
235endif
236
237if IO_DELAY_UDELAY
238config DEFAULT_IO_DELAY_TYPE
239	int
240	default IO_DELAY_TYPE_UDELAY
241endif
242
243if IO_DELAY_NONE
244config DEFAULT_IO_DELAY_TYPE
245	int
246	default IO_DELAY_TYPE_NONE
247endif
248
249config DEBUG_BOOT_PARAMS
250	bool "Debug boot parameters"
251	depends on DEBUG_KERNEL
252	depends on DEBUG_FS
253	---help---
254	  This option will cause struct boot_params to be exported via debugfs.
255
256config CPA_DEBUG
257	bool "CPA self-test code"
258	depends on DEBUG_KERNEL
259	---help---
260	  Do change_page_attr() self-tests every 30 seconds.
261
262config OPTIMIZE_INLINING
263	bool "Allow gcc to uninline functions marked 'inline'"
264	---help---
265	  This option determines if the kernel forces gcc to inline the functions
266	  developers have marked 'inline'. Doing so takes away freedom from gcc to
267	  do what it thinks is best, which is desirable for the gcc 3.x series of
268	  compilers. The gcc 4.x series have a rewritten inlining algorithm and
269	  enabling this option will generate a smaller kernel there. Hopefully
270	  this algorithm is so good that allowing gcc 4.x and above to make the
271	  decision will become the default in the future. Until then this option
272	  is there to test gcc for this.
273
274	  If unsure, say N.
275
276config DEBUG_STRICT_USER_COPY_CHECKS
277	bool "Strict copy size checks"
278	depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
279	---help---
280	  Enabling this option turns a certain set of sanity checks for user
281	  copy operations into compile time failures.
282
283	  The copy_from_user() etc checks are there to help test if there
284	  are sufficient security checks on the length argument of
285	  the copy operation, by having gcc prove that the argument is
286	  within bounds.
287
288	  If unsure, or if you run an older (pre 4.4) gcc, say N.
289
290config DEBUG_NMI_SELFTEST
291	bool "NMI Selftest"
292	depends on DEBUG_KERNEL && X86_LOCAL_APIC
293	---help---
294	  Enabling this option turns on a quick NMI selftest to verify
295	  that the NMI behaves correctly.
296
297	  This might help diagnose strange hangs that rely on NMI to
298	  function properly.
299
300	  If unsure, say N.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
301
302endmenu