xref: /linux/arch/xtensa/Kconfig (revision 7af710d988775aadf440222ecbe0c10eecf3eb54)
1# SPDX-License-Identifier: GPL-2.0
2config XTENSA
3	def_bool y
4	select ARCH_32BIT_OFF_T
5	select ARCH_HAS_BINFMT_FLAT if !MMU
6	select ARCH_HAS_SYNC_DMA_FOR_CPU
7	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
8	select ARCH_USE_QUEUED_RWLOCKS
9	select ARCH_USE_QUEUED_SPINLOCKS
10	select ARCH_WANT_FRAME_POINTERS
11	select ARCH_WANT_IPC_PARSE_VERSION
12	select BUILDTIME_EXTABLE_SORT
13	select CLONE_BACKWARDS
14	select COMMON_CLK
15	select DMA_REMAP if MMU
16	select GENERIC_ATOMIC64
17	select GENERIC_CLOCKEVENTS
18	select GENERIC_IRQ_SHOW
19	select GENERIC_PCI_IOMAP
20	select GENERIC_SCHED_CLOCK
21	select GENERIC_STRNCPY_FROM_USER if KASAN
22	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
23	select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
24	select HAVE_ARCH_TRACEHOOK
25	select HAVE_DEBUG_KMEMLEAK
26	select HAVE_DMA_CONTIGUOUS
27	select HAVE_EXIT_THREAD
28	select HAVE_FUNCTION_TRACER
29	select HAVE_FUTEX_CMPXCHG if !MMU
30	select HAVE_HW_BREAKPOINT if PERF_EVENTS
31	select HAVE_IRQ_TIME_ACCOUNTING
32	select HAVE_OPROFILE
33	select HAVE_PCI
34	select HAVE_PERF_EVENTS
35	select HAVE_STACKPROTECTOR
36	select HAVE_SYSCALL_TRACEPOINTS
37	select IRQ_DOMAIN
38	select MODULES_USE_ELF_RELA
39	select PERF_USE_VMALLOC
40	select VIRT_TO_BUS
41	help
42	  Xtensa processors are 32-bit RISC machines designed by Tensilica
43	  primarily for embedded systems.  These processors are both
44	  configurable and extensible.  The Linux port to the Xtensa
45	  architecture supports all processor configurations and extensions,
46	  with reasonable minimum requirements.  The Xtensa Linux project has
47	  a home page at <http://www.linux-xtensa.org/>.
48
49config GENERIC_HWEIGHT
50	def_bool y
51
52config ARCH_HAS_ILOG2_U32
53	def_bool n
54
55config ARCH_HAS_ILOG2_U64
56	def_bool n
57
58config NO_IOPORT_MAP
59	def_bool n
60
61config HZ
62	int
63	default 100
64
65config LOCKDEP_SUPPORT
66	def_bool y
67
68config STACKTRACE_SUPPORT
69	def_bool y
70
71config TRACE_IRQFLAGS_SUPPORT
72	def_bool y
73
74config MMU
75	def_bool n
76
77config HAVE_XTENSA_GPIO32
78	def_bool n
79
80config KASAN_SHADOW_OFFSET
81	hex
82	default 0x6e400000
83
84menu "Processor type and features"
85
86choice
87	prompt "Xtensa Processor Configuration"
88	default XTENSA_VARIANT_FSF
89
90config XTENSA_VARIANT_FSF
91	bool "fsf - default (not generic) configuration"
92	select MMU
93
94config XTENSA_VARIANT_DC232B
95	bool "dc232b - Diamond 232L Standard Core Rev.B (LE)"
96	select MMU
97	select HAVE_XTENSA_GPIO32
98	help
99	  This variant refers to Tensilica's Diamond 232L Standard core Rev.B (LE).
100
101config XTENSA_VARIANT_DC233C
102	bool "dc233c - Diamond 233L Standard Core Rev.C (LE)"
103	select MMU
104	select HAVE_XTENSA_GPIO32
105	help
106	  This variant refers to Tensilica's Diamond 233L Standard core Rev.C (LE).
107
108config XTENSA_VARIANT_CUSTOM
109	bool "Custom Xtensa processor configuration"
110	select HAVE_XTENSA_GPIO32
111	help
112	  Select this variant to use a custom Xtensa processor configuration.
113	  You will be prompted for a processor variant CORENAME.
114endchoice
115
116config XTENSA_VARIANT_CUSTOM_NAME
117	string "Xtensa Processor Custom Core Variant Name"
118	depends on XTENSA_VARIANT_CUSTOM
119	help
120	  Provide the name of a custom Xtensa processor variant.
121	  This CORENAME selects arch/xtensa/variant/CORENAME.
122	  Dont forget you have to select MMU if you have one.
123
124config XTENSA_VARIANT_NAME
125	string
126	default "dc232b"			if XTENSA_VARIANT_DC232B
127	default "dc233c"			if XTENSA_VARIANT_DC233C
128	default "fsf"				if XTENSA_VARIANT_FSF
129	default XTENSA_VARIANT_CUSTOM_NAME	if XTENSA_VARIANT_CUSTOM
130
131config XTENSA_VARIANT_MMU
132	bool "Core variant has a Full MMU (TLB, Pages, Protection, etc)"
133	depends on XTENSA_VARIANT_CUSTOM
134	default y
135	select MMU
136	help
137	  Build a Conventional Kernel with full MMU support,
138	  ie: it supports a TLB with auto-loading, page protection.
139
140config XTENSA_VARIANT_HAVE_PERF_EVENTS
141	bool "Core variant has Performance Monitor Module"
142	depends on XTENSA_VARIANT_CUSTOM
143	default n
144	help
145	  Enable if core variant has Performance Monitor Module with
146	  External Registers Interface.
147
148	  If unsure, say N.
149
150config XTENSA_FAKE_NMI
151	bool "Treat PMM IRQ as NMI"
152	depends on XTENSA_VARIANT_HAVE_PERF_EVENTS
153	default n
154	help
155	  If PMM IRQ is the only IRQ at EXCM level it is safe to
156	  treat it as NMI, which improves accuracy of profiling.
157
158	  If there are other interrupts at or above PMM IRQ priority level
159	  but not above the EXCM level, PMM IRQ still may be treated as NMI,
160	  but only if these IRQs are not used. There will be a build warning
161	  saying that this is not safe, and a bugcheck if one of these IRQs
162	  actually fire.
163
164	  If unsure, say N.
165
166config XTENSA_UNALIGNED_USER
167	bool "Unaligned memory access in user space"
168	help
169	  The Xtensa architecture currently does not handle unaligned
170	  memory accesses in hardware but through an exception handler.
171	  Per default, unaligned memory accesses are disabled in user space.
172
173	  Say Y here to enable unaligned memory access in user space.
174
175config HAVE_SMP
176	bool "System Supports SMP (MX)"
177	depends on XTENSA_VARIANT_CUSTOM
178	select XTENSA_MX
179	help
180	  This option is use to indicate that the system-on-a-chip (SOC)
181	  supports Multiprocessing. Multiprocessor support implemented above
182	  the CPU core definition and currently needs to be selected manually.
183
184	  Multiprocessor support in implemented with external cache and
185	  interrupt controllers.
186
187	  The MX interrupt distributer adds Interprocessor Interrupts
188	  and causes the IRQ numbers to be increased by 4 for devices
189	  like the open cores ethernet driver and the serial interface.
190
191	  You still have to select "Enable SMP" to enable SMP on this SOC.
192
193config SMP
194	bool "Enable Symmetric multi-processing support"
195	depends on HAVE_SMP
196	select GENERIC_SMP_IDLE_THREAD
197	help
198	  Enabled SMP Software; allows more than one CPU/CORE
199	  to be activated during startup.
200
201config NR_CPUS
202	depends on SMP
203	int "Maximum number of CPUs (2-32)"
204	range 2 32
205	default "4"
206
207config HOTPLUG_CPU
208	bool "Enable CPU hotplug support"
209	depends on SMP
210	help
211	  Say Y here to allow turning CPUs off and on. CPUs can be
212	  controlled through /sys/devices/system/cpu.
213
214	  Say N if you want to disable CPU hotplug.
215
216config FAST_SYSCALL_XTENSA
217	bool "Enable fast atomic syscalls"
218	default n
219	help
220	  fast_syscall_xtensa is a syscall that can make atomic operations
221	  on UP kernel when processor has no s32c1i support.
222
223	  This syscall is deprecated. It may have issues when called with
224	  invalid arguments. It is provided only for backwards compatibility.
225	  Only enable it if your userspace software requires it.
226
227	  If unsure, say N.
228
229config FAST_SYSCALL_SPILL_REGISTERS
230	bool "Enable spill registers syscall"
231	default n
232	help
233	  fast_syscall_spill_registers is a syscall that spills all active
234	  register windows of a calling userspace task onto its stack.
235
236	  This syscall is deprecated. It may have issues when called with
237	  invalid arguments. It is provided only for backwards compatibility.
238	  Only enable it if your userspace software requires it.
239
240	  If unsure, say N.
241
242config USER_ABI_CALL0
243	bool
244
245choice
246	prompt "Userspace ABI"
247	default USER_ABI_DEFAULT
248	help
249	  Select supported userspace ABI.
250
251	  If unsure, choose the default ABI.
252
253config USER_ABI_DEFAULT
254	bool "Default ABI only"
255	help
256	  Assume default userspace ABI. For XEA2 cores it is windowed ABI.
257	  call0 ABI binaries may be run on such kernel, but signal delivery
258	  will not work correctly for them.
259
260config USER_ABI_CALL0_ONLY
261	bool "Call0 ABI only"
262	select USER_ABI_CALL0
263	help
264	  Select this option to support only call0 ABI in userspace.
265	  Windowed ABI binaries will crash with a segfault caused by
266	  an illegal instruction exception on the first 'entry' opcode.
267
268	  Choose this option if you're planning to run only user code
269	  built with call0 ABI.
270
271config USER_ABI_CALL0_PROBE
272	bool "Support both windowed and call0 ABI by probing"
273	select USER_ABI_CALL0
274	help
275	  Select this option to support both windowed and call0 userspace
276	  ABIs. When enabled all processes are started with PS.WOE disabled
277	  and a fast user exception handler for an illegal instruction is
278	  used to turn on PS.WOE bit on the first 'entry' opcode executed by
279	  the userspace.
280
281	  This option should be enabled for the kernel that must support
282	  both call0 and windowed ABIs in userspace at the same time.
283
284	  Note that Xtensa ISA does not guarantee that entry opcode will
285	  raise an illegal instruction exception on cores with XEA2 when
286	  PS.WOE is disabled, check whether the target core supports it.
287
288endchoice
289
290endmenu
291
292config XTENSA_CALIBRATE_CCOUNT
293	def_bool n
294	help
295	  On some platforms (XT2000, for example), the CPU clock rate can
296	  vary.  The frequency can be determined, however, by measuring
297	  against a well known, fixed frequency, such as an UART oscillator.
298
299config SERIAL_CONSOLE
300	def_bool n
301
302config PLATFORM_HAVE_XIP
303	def_bool n
304
305menu "Platform options"
306
307choice
308	prompt "Xtensa System Type"
309	default XTENSA_PLATFORM_ISS
310
311config XTENSA_PLATFORM_ISS
312	bool "ISS"
313	select XTENSA_CALIBRATE_CCOUNT
314	select SERIAL_CONSOLE
315	help
316	  ISS is an acronym for Tensilica's Instruction Set Simulator.
317
318config XTENSA_PLATFORM_XT2000
319	bool "XT2000"
320	select HAVE_IDE
321	help
322	  XT2000 is the name of Tensilica's feature-rich emulation platform.
323	  This hardware is capable of running a full Linux distribution.
324
325config XTENSA_PLATFORM_XTFPGA
326	bool "XTFPGA"
327	select ETHOC if ETHERNET
328	select PLATFORM_WANT_DEFAULT_MEM if !MMU
329	select SERIAL_CONSOLE
330	select XTENSA_CALIBRATE_CCOUNT
331	select PLATFORM_HAVE_XIP
332	help
333	  XTFPGA is the name of Tensilica board family (LX60, LX110, LX200, ML605).
334	  This hardware is capable of running a full Linux distribution.
335
336endchoice
337
338config PLATFORM_NR_IRQS
339	int
340	default 3 if XTENSA_PLATFORM_XT2000
341	default 0
342
343config XTENSA_CPU_CLOCK
344	int "CPU clock rate [MHz]"
345	depends on !XTENSA_CALIBRATE_CCOUNT
346	default 16
347
348config GENERIC_CALIBRATE_DELAY
349	bool "Auto calibration of the BogoMIPS value"
350	help
351	  The BogoMIPS value can easily be derived from the CPU frequency.
352
353config CMDLINE_BOOL
354	bool "Default bootloader kernel arguments"
355
356config CMDLINE
357	string "Initial kernel command string"
358	depends on CMDLINE_BOOL
359	default "console=ttyS0,38400 root=/dev/ram"
360	help
361	  On some architectures (EBSA110 and CATS), there is currently no way
362	  for the boot loader to pass arguments to the kernel. For these
363	  architectures, you should supply some command-line options at build
364	  time by entering them here. As a minimum, you should specify the
365	  memory size and the root device (e.g., mem=64M root=/dev/nfs).
366
367config USE_OF
368	bool "Flattened Device Tree support"
369	select OF
370	select OF_EARLY_FLATTREE
371	help
372	  Include support for flattened device tree machine descriptions.
373
374config BUILTIN_DTB_SOURCE
375	string "DTB to build into the kernel image"
376	depends on OF
377
378config PARSE_BOOTPARAM
379	bool "Parse bootparam block"
380	default y
381	help
382	  Parse parameters passed to the kernel from the bootloader. It may
383	  be disabled if the kernel is known to run without the bootloader.
384
385	  If unsure, say Y.
386
387config BLK_DEV_SIMDISK
388	tristate "Host file-based simulated block device support"
389	default n
390	depends on XTENSA_PLATFORM_ISS && BLOCK
391	help
392	  Create block devices that map to files in the host file system.
393	  Device binding to host file may be changed at runtime via proc
394	  interface provided the device is not in use.
395
396config BLK_DEV_SIMDISK_COUNT
397	int "Number of host file-based simulated block devices"
398	range 1 10
399	depends on BLK_DEV_SIMDISK
400	default 2
401	help
402	  This is the default minimal number of created block devices.
403	  Kernel/module parameter 'simdisk_count' may be used to change this
404	  value at runtime. More file names (but no more than 10) may be
405	  specified as parameters, simdisk_count grows accordingly.
406
407config SIMDISK0_FILENAME
408	string "Host filename for the first simulated device"
409	depends on BLK_DEV_SIMDISK = y
410	default ""
411	help
412	  Attach a first simdisk to a host file. Conventionally, this file
413	  contains a root file system.
414
415config SIMDISK1_FILENAME
416	string "Host filename for the second simulated device"
417	depends on BLK_DEV_SIMDISK = y && BLK_DEV_SIMDISK_COUNT != 1
418	default ""
419	help
420	  Another simulated disk in a host file for a buildroot-independent
421	  storage.
422
423config XTFPGA_LCD
424	bool "Enable XTFPGA LCD driver"
425	depends on XTENSA_PLATFORM_XTFPGA
426	default n
427	help
428	  There's a 2x16 LCD on most of XTFPGA boards, kernel may output
429	  progress messages there during bootup/shutdown. It may be useful
430	  during board bringup.
431
432	  If unsure, say N.
433
434config XTFPGA_LCD_BASE_ADDR
435	hex "XTFPGA LCD base address"
436	depends on XTFPGA_LCD
437	default "0x0d0c0000"
438	help
439	  Base address of the LCD controller inside KIO region.
440	  Different boards from XTFPGA family have LCD controller at different
441	  addresses. Please consult prototyping user guide for your board for
442	  the correct address. Wrong address here may lead to hardware lockup.
443
444config XTFPGA_LCD_8BIT_ACCESS
445	bool "Use 8-bit access to XTFPGA LCD"
446	depends on XTFPGA_LCD
447	default n
448	help
449	  LCD may be connected with 4- or 8-bit interface, 8-bit access may
450	  only be used with 8-bit interface. Please consult prototyping user
451	  guide for your board for the correct interface width.
452
453comment "Kernel memory layout"
454
455config INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
456	bool "Initialize Xtensa MMU inside the Linux kernel code"
457	depends on !XTENSA_VARIANT_FSF && !XTENSA_VARIANT_DC232B
458	default y if XTENSA_VARIANT_DC233C || XTENSA_VARIANT_CUSTOM
459	help
460	  Earlier version initialized the MMU in the exception vector
461	  before jumping to _startup in head.S and had an advantage that
462	  it was possible to place a software breakpoint at 'reset' and
463	  then enter your normal kernel breakpoints once the MMU was mapped
464	  to the kernel mappings (0XC0000000).
465
466	  This unfortunately won't work for U-Boot and likely also wont
467	  work for using KEXEC to have a hot kernel ready for doing a
468	  KDUMP.
469
470	  So now the MMU is initialized in head.S but it's necessary to
471	  use hardware breakpoints (gdb 'hbreak' cmd) to break at _startup.
472	  xt-gdb can't place a Software Breakpoint in the  0XD region prior
473	  to mapping the MMU and after mapping even if the area of low memory
474	  was mapped gdb wouldn't remove the breakpoint on hitting it as the
475	  PC wouldn't match. Since Hardware Breakpoints are recommended for
476	  Linux configurations it seems reasonable to just assume they exist
477	  and leave this older mechanism for unfortunate souls that choose
478	  not to follow Tensilica's recommendation.
479
480	  Selecting this will cause U-Boot to set the KERNEL Load and Entry
481	  address at 0x00003000 instead of the mapped std of 0xD0003000.
482
483	  If in doubt, say Y.
484
485config XIP_KERNEL
486	bool "Kernel Execute-In-Place from ROM"
487	depends on PLATFORM_HAVE_XIP
488	help
489	  Execute-In-Place allows the kernel to run from non-volatile storage
490	  directly addressable by the CPU, such as NOR flash. This saves RAM
491	  space since the text section of the kernel is not loaded from flash
492	  to RAM. Read-write sections, such as the data section and stack,
493	  are still copied to RAM. The XIP kernel is not compressed since
494	  it has to run directly from flash, so it will take more space to
495	  store it. The flash address used to link the kernel object files,
496	  and for storing it, is configuration dependent. Therefore, if you
497	  say Y here, you must know the proper physical address where to
498	  store the kernel image depending on your own flash memory usage.
499
500	  Also note that the make target becomes "make xipImage" rather than
501	  "make Image" or "make uImage". The final kernel binary to put in
502	  ROM memory will be arch/xtensa/boot/xipImage.
503
504	  If unsure, say N.
505
506config MEMMAP_CACHEATTR
507	hex "Cache attributes for the memory address space"
508	depends on !MMU
509	default 0x22222222
510	help
511	  These cache attributes are set up for noMMU systems. Each hex digit
512	  specifies cache attributes for the corresponding 512MB memory
513	  region: bits 0..3 -- for addresses 0x00000000..0x1fffffff,
514	  bits 4..7 -- for addresses 0x20000000..0x3fffffff, and so on.
515
516	  Cache attribute values are specific for the MMU type.
517	  For region protection MMUs:
518	    1: WT cached,
519	    2: cache bypass,
520	    4: WB cached,
521	    f: illegal.
522	  For ful MMU:
523	    bit 0: executable,
524	    bit 1: writable,
525	    bits 2..3:
526	      0: cache bypass,
527	      1: WB cache,
528	      2: WT cache,
529	      3: special (c and e are illegal, f is reserved).
530	  For MPU:
531	    0: illegal,
532	    1: WB cache,
533	    2: WB, no-write-allocate cache,
534	    3: WT cache,
535	    4: cache bypass.
536
537config KSEG_PADDR
538	hex "Physical address of the KSEG mapping"
539	depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX && MMU
540	default 0x00000000
541	help
542	  This is the physical address where KSEG is mapped. Please refer to
543	  the chosen KSEG layout help for the required address alignment.
544	  Unpacked kernel image (including vectors) must be located completely
545	  within KSEG.
546	  Physical memory below this address is not available to linux.
547
548	  If unsure, leave the default value here.
549
550config KERNEL_VIRTUAL_ADDRESS
551	hex "Kernel virtual address"
552	depends on MMU && XIP_KERNEL
553	default 0xd0003000
554	help
555	  This is the virtual address where the XIP kernel is mapped.
556	  XIP kernel may be mapped into KSEG or KIO region, virtual address
557	  provided here must match kernel load address provided in
558	  KERNEL_LOAD_ADDRESS.
559
560config KERNEL_LOAD_ADDRESS
561	hex "Kernel load address"
562	default 0x60003000 if !MMU
563	default 0x00003000 if MMU && INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
564	default 0xd0003000 if MMU && !INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
565	help
566	  This is the address where the kernel is loaded.
567	  It is virtual address for MMUv2 configurations and physical address
568	  for all other configurations.
569
570	  If unsure, leave the default value here.
571
572config VECTORS_OFFSET
573	hex "Kernel vectors offset"
574	default 0x00003000
575	depends on !XIP_KERNEL
576	help
577	  This is the offset of the kernel image from the relocatable vectors
578	  base.
579
580	  If unsure, leave the default value here.
581
582config XIP_DATA_ADDR
583	hex "XIP kernel data virtual address"
584	depends on XIP_KERNEL
585	default 0x00000000
586	help
587	  This is the virtual address where XIP kernel data is copied.
588	  It must be within KSEG if MMU is used.
589
590config PLATFORM_WANT_DEFAULT_MEM
591	def_bool n
592
593config DEFAULT_MEM_START
594	hex
595	prompt "PAGE_OFFSET/PHYS_OFFSET" if !MMU && PLATFORM_WANT_DEFAULT_MEM
596	default 0x60000000 if PLATFORM_WANT_DEFAULT_MEM
597	default 0x00000000
598	help
599	  This is the base address used for both PAGE_OFFSET and PHYS_OFFSET
600	  in noMMU configurations.
601
602	  If unsure, leave the default value here.
603
604choice
605	prompt "KSEG layout"
606	depends on MMU
607	default XTENSA_KSEG_MMU_V2
608
609config XTENSA_KSEG_MMU_V2
610	bool "MMUv2: 128MB cached + 128MB uncached"
611	help
612	  MMUv2 compatible kernel memory map: TLB way 5 maps 128MB starting
613	  at KSEG_PADDR to 0xd0000000 with cache and to 0xd8000000
614	  without cache.
615	  KSEG_PADDR must be aligned to 128MB.
616
617config XTENSA_KSEG_256M
618	bool "256MB cached + 256MB uncached"
619	depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
620	help
621	  TLB way 6 maps 256MB starting at KSEG_PADDR to 0xb0000000
622	  with cache and to 0xc0000000 without cache.
623	  KSEG_PADDR must be aligned to 256MB.
624
625config XTENSA_KSEG_512M
626	bool "512MB cached + 512MB uncached"
627	depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
628	help
629	  TLB way 6 maps 512MB starting at KSEG_PADDR to 0xa0000000
630	  with cache and to 0xc0000000 without cache.
631	  KSEG_PADDR must be aligned to 256MB.
632
633endchoice
634
635config HIGHMEM
636	bool "High Memory Support"
637	depends on MMU
638	help
639	  Linux can use the full amount of RAM in the system by
640	  default. However, the default MMUv2 setup only maps the
641	  lowermost 128 MB of memory linearly to the areas starting
642	  at 0xd0000000 (cached) and 0xd8000000 (uncached).
643	  When there are more than 128 MB memory in the system not
644	  all of it can be "permanently mapped" by the kernel.
645	  The physical memory that's not permanently mapped is called
646	  "high memory".
647
648	  If you are compiling a kernel which will never run on a
649	  machine with more than 128 MB total physical RAM, answer
650	  N here.
651
652	  If unsure, say Y.
653
654config FORCE_MAX_ZONEORDER
655	int "Maximum zone order"
656	default "11"
657	help
658	  The kernel memory allocator divides physically contiguous memory
659	  blocks into "zones", where each zone is a power of two number of
660	  pages.  This option selects the largest power of two that the kernel
661	  keeps in the memory allocator.  If you need to allocate very large
662	  blocks of physically contiguous memory, then you may need to
663	  increase this value.
664
665	  This config option is actually maximum order plus one. For example,
666	  a value of 11 means that the largest free memory block is 2^10 pages.
667
668endmenu
669
670menu "Power management options"
671
672source "kernel/power/Kconfig"
673
674endmenu
675