xref: /openbmc/linux/arch/xtensa/Kconfig (revision 95298d63)
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_DMA_PREP_COHERENT if MMU
7	select ARCH_HAS_SYNC_DMA_FOR_CPU if MMU
8	select ARCH_HAS_SYNC_DMA_FOR_DEVICE if MMU
9	select ARCH_HAS_DMA_SET_UNCACHED if MMU
10	select ARCH_USE_QUEUED_RWLOCKS
11	select ARCH_USE_QUEUED_SPINLOCKS
12	select ARCH_WANT_FRAME_POINTERS
13	select ARCH_WANT_IPC_PARSE_VERSION
14	select BUILDTIME_TABLE_SORT
15	select CLONE_BACKWARDS
16	select COMMON_CLK
17	select DMA_REMAP if MMU
18	select GENERIC_ATOMIC64
19	select GENERIC_CLOCKEVENTS
20	select GENERIC_IRQ_SHOW
21	select GENERIC_PCI_IOMAP
22	select GENERIC_SCHED_CLOCK
23	select GENERIC_STRNCPY_FROM_USER if KASAN
24	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
25	select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
26	select HAVE_ARCH_TRACEHOOK
27	select HAVE_COPY_THREAD_TLS
28	select HAVE_DEBUG_KMEMLEAK
29	select HAVE_DMA_CONTIGUOUS
30	select HAVE_EXIT_THREAD
31	select HAVE_FUNCTION_TRACER
32	select HAVE_FUTEX_CMPXCHG if !MMU
33	select HAVE_HW_BREAKPOINT if PERF_EVENTS
34	select HAVE_IRQ_TIME_ACCOUNTING
35	select HAVE_OPROFILE
36	select HAVE_PCI
37	select HAVE_PERF_EVENTS
38	select HAVE_STACKPROTECTOR
39	select HAVE_SYSCALL_TRACEPOINTS
40	select IRQ_DOMAIN
41	select MODULES_USE_ELF_RELA
42	select PERF_USE_VMALLOC
43	select VIRT_TO_BUS
44	help
45	  Xtensa processors are 32-bit RISC machines designed by Tensilica
46	  primarily for embedded systems.  These processors are both
47	  configurable and extensible.  The Linux port to the Xtensa
48	  architecture supports all processor configurations and extensions,
49	  with reasonable minimum requirements.  The Xtensa Linux project has
50	  a home page at <http://www.linux-xtensa.org/>.
51
52config GENERIC_HWEIGHT
53	def_bool y
54
55config ARCH_HAS_ILOG2_U32
56	def_bool n
57
58config ARCH_HAS_ILOG2_U64
59	def_bool n
60
61config NO_IOPORT_MAP
62	def_bool n
63
64config HZ
65	int
66	default 100
67
68config LOCKDEP_SUPPORT
69	def_bool y
70
71config STACKTRACE_SUPPORT
72	def_bool y
73
74config TRACE_IRQFLAGS_SUPPORT
75	def_bool y
76
77config MMU
78	def_bool n
79
80config HAVE_XTENSA_GPIO32
81	def_bool n
82
83config KASAN_SHADOW_OFFSET
84	hex
85	default 0x6e400000
86
87menu "Processor type and features"
88
89choice
90	prompt "Xtensa Processor Configuration"
91	default XTENSA_VARIANT_FSF
92
93config XTENSA_VARIANT_FSF
94	bool "fsf - default (not generic) configuration"
95	select MMU
96
97config XTENSA_VARIANT_DC232B
98	bool "dc232b - Diamond 232L Standard Core Rev.B (LE)"
99	select MMU
100	select HAVE_XTENSA_GPIO32
101	help
102	  This variant refers to Tensilica's Diamond 232L Standard core Rev.B (LE).
103
104config XTENSA_VARIANT_DC233C
105	bool "dc233c - Diamond 233L Standard Core Rev.C (LE)"
106	select MMU
107	select HAVE_XTENSA_GPIO32
108	help
109	  This variant refers to Tensilica's Diamond 233L Standard core Rev.C (LE).
110
111config XTENSA_VARIANT_CUSTOM
112	bool "Custom Xtensa processor configuration"
113	select HAVE_XTENSA_GPIO32
114	help
115	  Select this variant to use a custom Xtensa processor configuration.
116	  You will be prompted for a processor variant CORENAME.
117endchoice
118
119config XTENSA_VARIANT_CUSTOM_NAME
120	string "Xtensa Processor Custom Core Variant Name"
121	depends on XTENSA_VARIANT_CUSTOM
122	help
123	  Provide the name of a custom Xtensa processor variant.
124	  This CORENAME selects arch/xtensa/variant/CORENAME.
125	  Don't forget you have to select MMU if you have one.
126
127config XTENSA_VARIANT_NAME
128	string
129	default "dc232b"			if XTENSA_VARIANT_DC232B
130	default "dc233c"			if XTENSA_VARIANT_DC233C
131	default "fsf"				if XTENSA_VARIANT_FSF
132	default XTENSA_VARIANT_CUSTOM_NAME	if XTENSA_VARIANT_CUSTOM
133
134config XTENSA_VARIANT_MMU
135	bool "Core variant has a Full MMU (TLB, Pages, Protection, etc)"
136	depends on XTENSA_VARIANT_CUSTOM
137	default y
138	select MMU
139	help
140	  Build a Conventional Kernel with full MMU support,
141	  ie: it supports a TLB with auto-loading, page protection.
142
143config XTENSA_VARIANT_HAVE_PERF_EVENTS
144	bool "Core variant has Performance Monitor Module"
145	depends on XTENSA_VARIANT_CUSTOM
146	default n
147	help
148	  Enable if core variant has Performance Monitor Module with
149	  External Registers Interface.
150
151	  If unsure, say N.
152
153config XTENSA_FAKE_NMI
154	bool "Treat PMM IRQ as NMI"
155	depends on XTENSA_VARIANT_HAVE_PERF_EVENTS
156	default n
157	help
158	  If PMM IRQ is the only IRQ at EXCM level it is safe to
159	  treat it as NMI, which improves accuracy of profiling.
160
161	  If there are other interrupts at or above PMM IRQ priority level
162	  but not above the EXCM level, PMM IRQ still may be treated as NMI,
163	  but only if these IRQs are not used. There will be a build warning
164	  saying that this is not safe, and a bugcheck if one of these IRQs
165	  actually fire.
166
167	  If unsure, say N.
168
169config XTENSA_UNALIGNED_USER
170	bool "Unaligned memory access in user space"
171	help
172	  The Xtensa architecture currently does not handle unaligned
173	  memory accesses in hardware but through an exception handler.
174	  Per default, unaligned memory accesses are disabled in user space.
175
176	  Say Y here to enable unaligned memory access in user space.
177
178config HAVE_SMP
179	bool "System Supports SMP (MX)"
180	depends on XTENSA_VARIANT_CUSTOM
181	select XTENSA_MX
182	help
183	  This option is used to indicate that the system-on-a-chip (SOC)
184	  supports Multiprocessing. Multiprocessor support implemented above
185	  the CPU core definition and currently needs to be selected manually.
186
187	  Multiprocessor support is implemented with external cache and
188	  interrupt controllers.
189
190	  The MX interrupt distributer adds Interprocessor Interrupts
191	  and causes the IRQ numbers to be increased by 4 for devices
192	  like the open cores ethernet driver and the serial interface.
193
194	  You still have to select "Enable SMP" to enable SMP on this SOC.
195
196config SMP
197	bool "Enable Symmetric multi-processing support"
198	depends on HAVE_SMP
199	select GENERIC_SMP_IDLE_THREAD
200	help
201	  Enabled SMP Software; allows more than one CPU/CORE
202	  to be activated during startup.
203
204config NR_CPUS
205	depends on SMP
206	int "Maximum number of CPUs (2-32)"
207	range 2 32
208	default "4"
209
210config HOTPLUG_CPU
211	bool "Enable CPU hotplug support"
212	depends on SMP
213	help
214	  Say Y here to allow turning CPUs off and on. CPUs can be
215	  controlled through /sys/devices/system/cpu.
216
217	  Say N if you want to disable CPU hotplug.
218
219config FAST_SYSCALL_XTENSA
220	bool "Enable fast atomic syscalls"
221	default n
222	help
223	  fast_syscall_xtensa is a syscall that can make atomic operations
224	  on UP kernel when processor has no s32c1i support.
225
226	  This syscall is deprecated. It may have issues when called with
227	  invalid arguments. It is provided only for backwards compatibility.
228	  Only enable it if your userspace software requires it.
229
230	  If unsure, say N.
231
232config FAST_SYSCALL_SPILL_REGISTERS
233	bool "Enable spill registers syscall"
234	default n
235	help
236	  fast_syscall_spill_registers is a syscall that spills all active
237	  register windows of a calling userspace task onto its stack.
238
239	  This syscall is deprecated. It may have issues when called with
240	  invalid arguments. It is provided only for backwards compatibility.
241	  Only enable it if your userspace software requires it.
242
243	  If unsure, say N.
244
245config USER_ABI_CALL0
246	bool
247
248choice
249	prompt "Userspace ABI"
250	default USER_ABI_DEFAULT
251	help
252	  Select supported userspace ABI.
253
254	  If unsure, choose the default ABI.
255
256config USER_ABI_DEFAULT
257	bool "Default ABI only"
258	help
259	  Assume default userspace ABI. For XEA2 cores it is windowed ABI.
260	  call0 ABI binaries may be run on such kernel, but signal delivery
261	  will not work correctly for them.
262
263config USER_ABI_CALL0_ONLY
264	bool "Call0 ABI only"
265	select USER_ABI_CALL0
266	help
267	  Select this option to support only call0 ABI in userspace.
268	  Windowed ABI binaries will crash with a segfault caused by
269	  an illegal instruction exception on the first 'entry' opcode.
270
271	  Choose this option if you're planning to run only user code
272	  built with call0 ABI.
273
274config USER_ABI_CALL0_PROBE
275	bool "Support both windowed and call0 ABI by probing"
276	select USER_ABI_CALL0
277	help
278	  Select this option to support both windowed and call0 userspace
279	  ABIs. When enabled all processes are started with PS.WOE disabled
280	  and a fast user exception handler for an illegal instruction is
281	  used to turn on PS.WOE bit on the first 'entry' opcode executed by
282	  the userspace.
283
284	  This option should be enabled for the kernel that must support
285	  both call0 and windowed ABIs in userspace at the same time.
286
287	  Note that Xtensa ISA does not guarantee that entry opcode will
288	  raise an illegal instruction exception on cores with XEA2 when
289	  PS.WOE is disabled, check whether the target core supports it.
290
291endchoice
292
293endmenu
294
295config XTENSA_CALIBRATE_CCOUNT
296	def_bool n
297	help
298	  On some platforms (XT2000, for example), the CPU clock rate can
299	  vary.  The frequency can be determined, however, by measuring
300	  against a well known, fixed frequency, such as an UART oscillator.
301
302config SERIAL_CONSOLE
303	def_bool n
304
305config PLATFORM_HAVE_XIP
306	def_bool n
307
308menu "Platform options"
309
310choice
311	prompt "Xtensa System Type"
312	default XTENSA_PLATFORM_ISS
313
314config XTENSA_PLATFORM_ISS
315	bool "ISS"
316	select XTENSA_CALIBRATE_CCOUNT
317	select SERIAL_CONSOLE
318	help
319	  ISS is an acronym for Tensilica's Instruction Set Simulator.
320
321config XTENSA_PLATFORM_XT2000
322	bool "XT2000"
323	select HAVE_IDE
324	help
325	  XT2000 is the name of Tensilica's feature-rich emulation platform.
326	  This hardware is capable of running a full Linux distribution.
327
328config XTENSA_PLATFORM_XTFPGA
329	bool "XTFPGA"
330	select ETHOC if ETHERNET
331	select PLATFORM_WANT_DEFAULT_MEM if !MMU
332	select SERIAL_CONSOLE
333	select XTENSA_CALIBRATE_CCOUNT
334	select PLATFORM_HAVE_XIP
335	help
336	  XTFPGA is the name of Tensilica board family (LX60, LX110, LX200, ML605).
337	  This hardware is capable of running a full Linux distribution.
338
339endchoice
340
341config PLATFORM_NR_IRQS
342	int
343	default 3 if XTENSA_PLATFORM_XT2000
344	default 0
345
346config XTENSA_CPU_CLOCK
347	int "CPU clock rate [MHz]"
348	depends on !XTENSA_CALIBRATE_CCOUNT
349	default 16
350
351config GENERIC_CALIBRATE_DELAY
352	bool "Auto calibration of the BogoMIPS value"
353	help
354	  The BogoMIPS value can easily be derived from the CPU frequency.
355
356config CMDLINE_BOOL
357	bool "Default bootloader kernel arguments"
358
359config CMDLINE
360	string "Initial kernel command string"
361	depends on CMDLINE_BOOL
362	default "console=ttyS0,38400 root=/dev/ram"
363	help
364	  On some architectures (EBSA110 and CATS), there is currently no way
365	  for the boot loader to pass arguments to the kernel. For these
366	  architectures, you should supply some command-line options at build
367	  time by entering them here. As a minimum, you should specify the
368	  memory size and the root device (e.g., mem=64M root=/dev/nfs).
369
370config USE_OF
371	bool "Flattened Device Tree support"
372	select OF
373	select OF_EARLY_FLATTREE
374	help
375	  Include support for flattened device tree machine descriptions.
376
377config BUILTIN_DTB_SOURCE
378	string "DTB to build into the kernel image"
379	depends on OF
380
381config PARSE_BOOTPARAM
382	bool "Parse bootparam block"
383	default y
384	help
385	  Parse parameters passed to the kernel from the bootloader. It may
386	  be disabled if the kernel is known to run without the bootloader.
387
388	  If unsure, say Y.
389
390config BLK_DEV_SIMDISK
391	tristate "Host file-based simulated block device support"
392	default n
393	depends on XTENSA_PLATFORM_ISS && BLOCK
394	help
395	  Create block devices that map to files in the host file system.
396	  Device binding to host file may be changed at runtime via proc
397	  interface provided the device is not in use.
398
399config BLK_DEV_SIMDISK_COUNT
400	int "Number of host file-based simulated block devices"
401	range 1 10
402	depends on BLK_DEV_SIMDISK
403	default 2
404	help
405	  This is the default minimal number of created block devices.
406	  Kernel/module parameter 'simdisk_count' may be used to change this
407	  value at runtime. More file names (but no more than 10) may be
408	  specified as parameters, simdisk_count grows accordingly.
409
410config SIMDISK0_FILENAME
411	string "Host filename for the first simulated device"
412	depends on BLK_DEV_SIMDISK = y
413	default ""
414	help
415	  Attach a first simdisk to a host file. Conventionally, this file
416	  contains a root file system.
417
418config SIMDISK1_FILENAME
419	string "Host filename for the second simulated device"
420	depends on BLK_DEV_SIMDISK = y && BLK_DEV_SIMDISK_COUNT != 1
421	default ""
422	help
423	  Another simulated disk in a host file for a buildroot-independent
424	  storage.
425
426config XTFPGA_LCD
427	bool "Enable XTFPGA LCD driver"
428	depends on XTENSA_PLATFORM_XTFPGA
429	default n
430	help
431	  There's a 2x16 LCD on most of XTFPGA boards, kernel may output
432	  progress messages there during bootup/shutdown. It may be useful
433	  during board bringup.
434
435	  If unsure, say N.
436
437config XTFPGA_LCD_BASE_ADDR
438	hex "XTFPGA LCD base address"
439	depends on XTFPGA_LCD
440	default "0x0d0c0000"
441	help
442	  Base address of the LCD controller inside KIO region.
443	  Different boards from XTFPGA family have LCD controller at different
444	  addresses. Please consult prototyping user guide for your board for
445	  the correct address. Wrong address here may lead to hardware lockup.
446
447config XTFPGA_LCD_8BIT_ACCESS
448	bool "Use 8-bit access to XTFPGA LCD"
449	depends on XTFPGA_LCD
450	default n
451	help
452	  LCD may be connected with 4- or 8-bit interface, 8-bit access may
453	  only be used with 8-bit interface. Please consult prototyping user
454	  guide for your board for the correct interface width.
455
456comment "Kernel memory layout"
457
458config INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
459	bool "Initialize Xtensa MMU inside the Linux kernel code"
460	depends on !XTENSA_VARIANT_FSF && !XTENSA_VARIANT_DC232B
461	default y if XTENSA_VARIANT_DC233C || XTENSA_VARIANT_CUSTOM
462	help
463	  Earlier version initialized the MMU in the exception vector
464	  before jumping to _startup in head.S and had an advantage that
465	  it was possible to place a software breakpoint at 'reset' and
466	  then enter your normal kernel breakpoints once the MMU was mapped
467	  to the kernel mappings (0XC0000000).
468
469	  This unfortunately won't work for U-Boot and likely also wont
470	  work for using KEXEC to have a hot kernel ready for doing a
471	  KDUMP.
472
473	  So now the MMU is initialized in head.S but it's necessary to
474	  use hardware breakpoints (gdb 'hbreak' cmd) to break at _startup.
475	  xt-gdb can't place a Software Breakpoint in the  0XD region prior
476	  to mapping the MMU and after mapping even if the area of low memory
477	  was mapped gdb wouldn't remove the breakpoint on hitting it as the
478	  PC wouldn't match. Since Hardware Breakpoints are recommended for
479	  Linux configurations it seems reasonable to just assume they exist
480	  and leave this older mechanism for unfortunate souls that choose
481	  not to follow Tensilica's recommendation.
482
483	  Selecting this will cause U-Boot to set the KERNEL Load and Entry
484	  address at 0x00003000 instead of the mapped std of 0xD0003000.
485
486	  If in doubt, say Y.
487
488config XIP_KERNEL
489	bool "Kernel Execute-In-Place from ROM"
490	depends on PLATFORM_HAVE_XIP
491	help
492	  Execute-In-Place allows the kernel to run from non-volatile storage
493	  directly addressable by the CPU, such as NOR flash. This saves RAM
494	  space since the text section of the kernel is not loaded from flash
495	  to RAM. Read-write sections, such as the data section and stack,
496	  are still copied to RAM. The XIP kernel is not compressed since
497	  it has to run directly from flash, so it will take more space to
498	  store it. The flash address used to link the kernel object files,
499	  and for storing it, is configuration dependent. Therefore, if you
500	  say Y here, you must know the proper physical address where to
501	  store the kernel image depending on your own flash memory usage.
502
503	  Also note that the make target becomes "make xipImage" rather than
504	  "make Image" or "make uImage". The final kernel binary to put in
505	  ROM memory will be arch/xtensa/boot/xipImage.
506
507	  If unsure, say N.
508
509config MEMMAP_CACHEATTR
510	hex "Cache attributes for the memory address space"
511	depends on !MMU
512	default 0x22222222
513	help
514	  These cache attributes are set up for noMMU systems. Each hex digit
515	  specifies cache attributes for the corresponding 512MB memory
516	  region: bits 0..3 -- for addresses 0x00000000..0x1fffffff,
517	  bits 4..7 -- for addresses 0x20000000..0x3fffffff, and so on.
518
519	  Cache attribute values are specific for the MMU type.
520	  For region protection MMUs:
521	    1: WT cached,
522	    2: cache bypass,
523	    4: WB cached,
524	    f: illegal.
525	  For ful MMU:
526	    bit 0: executable,
527	    bit 1: writable,
528	    bits 2..3:
529	      0: cache bypass,
530	      1: WB cache,
531	      2: WT cache,
532	      3: special (c and e are illegal, f is reserved).
533	  For MPU:
534	    0: illegal,
535	    1: WB cache,
536	    2: WB, no-write-allocate cache,
537	    3: WT cache,
538	    4: cache bypass.
539
540config KSEG_PADDR
541	hex "Physical address of the KSEG mapping"
542	depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX && MMU
543	default 0x00000000
544	help
545	  This is the physical address where KSEG is mapped. Please refer to
546	  the chosen KSEG layout help for the required address alignment.
547	  Unpacked kernel image (including vectors) must be located completely
548	  within KSEG.
549	  Physical memory below this address is not available to linux.
550
551	  If unsure, leave the default value here.
552
553config KERNEL_VIRTUAL_ADDRESS
554	hex "Kernel virtual address"
555	depends on MMU && XIP_KERNEL
556	default 0xd0003000
557	help
558	  This is the virtual address where the XIP kernel is mapped.
559	  XIP kernel may be mapped into KSEG or KIO region, virtual address
560	  provided here must match kernel load address provided in
561	  KERNEL_LOAD_ADDRESS.
562
563config KERNEL_LOAD_ADDRESS
564	hex "Kernel load address"
565	default 0x60003000 if !MMU
566	default 0x00003000 if MMU && INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
567	default 0xd0003000 if MMU && !INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
568	help
569	  This is the address where the kernel is loaded.
570	  It is virtual address for MMUv2 configurations and physical address
571	  for all other configurations.
572
573	  If unsure, leave the default value here.
574
575choice
576	prompt "Relocatable vectors location"
577	default XTENSA_VECTORS_IN_TEXT
578	help
579	  Choose whether relocatable vectors are merged into the kernel .text
580	  or placed separately at runtime. This option does not affect
581	  configurations without VECBASE register where vectors are always
582	  placed at their hardware-defined locations.
583
584config XTENSA_VECTORS_IN_TEXT
585	bool "Merge relocatable vectors into kernel text"
586	depends on !MTD_XIP
587	help
588	  This option puts relocatable vectors into the kernel .text section
589	  with proper alignment.
590	  This is a safe choice for most configurations.
591
592config XTENSA_VECTORS_SEPARATE
593	bool "Put relocatable vectors at fixed address"
594	help
595	  This option puts relocatable vectors at specific virtual address.
596	  Vectors are merged with the .init data in the kernel image and
597	  are copied into their designated location during kernel startup.
598	  Use it to put vectors into IRAM or out of FLASH on kernels with
599	  XIP-aware MTD support.
600
601endchoice
602
603config VECTORS_ADDR
604	hex "Kernel vectors virtual address"
605	default 0x00000000
606	depends on XTENSA_VECTORS_SEPARATE
607	help
608	  This is the virtual address of the (relocatable) vectors base.
609	  It must be within KSEG if MMU is used.
610
611config XIP_DATA_ADDR
612	hex "XIP kernel data virtual address"
613	depends on XIP_KERNEL
614	default 0x00000000
615	help
616	  This is the virtual address where XIP kernel data is copied.
617	  It must be within KSEG if MMU is used.
618
619config PLATFORM_WANT_DEFAULT_MEM
620	def_bool n
621
622config DEFAULT_MEM_START
623	hex
624	prompt "PAGE_OFFSET/PHYS_OFFSET" if !MMU && PLATFORM_WANT_DEFAULT_MEM
625	default 0x60000000 if PLATFORM_WANT_DEFAULT_MEM
626	default 0x00000000
627	help
628	  This is the base address used for both PAGE_OFFSET and PHYS_OFFSET
629	  in noMMU configurations.
630
631	  If unsure, leave the default value here.
632
633choice
634	prompt "KSEG layout"
635	depends on MMU
636	default XTENSA_KSEG_MMU_V2
637
638config XTENSA_KSEG_MMU_V2
639	bool "MMUv2: 128MB cached + 128MB uncached"
640	help
641	  MMUv2 compatible kernel memory map: TLB way 5 maps 128MB starting
642	  at KSEG_PADDR to 0xd0000000 with cache and to 0xd8000000
643	  without cache.
644	  KSEG_PADDR must be aligned to 128MB.
645
646config XTENSA_KSEG_256M
647	bool "256MB cached + 256MB uncached"
648	depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
649	help
650	  TLB way 6 maps 256MB starting at KSEG_PADDR to 0xb0000000
651	  with cache and to 0xc0000000 without cache.
652	  KSEG_PADDR must be aligned to 256MB.
653
654config XTENSA_KSEG_512M
655	bool "512MB cached + 512MB uncached"
656	depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
657	help
658	  TLB way 6 maps 512MB starting at KSEG_PADDR to 0xa0000000
659	  with cache and to 0xc0000000 without cache.
660	  KSEG_PADDR must be aligned to 256MB.
661
662endchoice
663
664config HIGHMEM
665	bool "High Memory Support"
666	depends on MMU
667	help
668	  Linux can use the full amount of RAM in the system by
669	  default. However, the default MMUv2 setup only maps the
670	  lowermost 128 MB of memory linearly to the areas starting
671	  at 0xd0000000 (cached) and 0xd8000000 (uncached).
672	  When there are more than 128 MB memory in the system not
673	  all of it can be "permanently mapped" by the kernel.
674	  The physical memory that's not permanently mapped is called
675	  "high memory".
676
677	  If you are compiling a kernel which will never run on a
678	  machine with more than 128 MB total physical RAM, answer
679	  N here.
680
681	  If unsure, say Y.
682
683config FORCE_MAX_ZONEORDER
684	int "Maximum zone order"
685	default "11"
686	help
687	  The kernel memory allocator divides physically contiguous memory
688	  blocks into "zones", where each zone is a power of two number of
689	  pages.  This option selects the largest power of two that the kernel
690	  keeps in the memory allocator.  If you need to allocate very large
691	  blocks of physically contiguous memory, then you may need to
692	  increase this value.
693
694	  This config option is actually maximum order plus one. For example,
695	  a value of 11 means that the largest free memory block is 2^10 pages.
696
697endmenu
698
699menu "Power management options"
700
701source "kernel/power/Kconfig"
702
703endmenu
704