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_AUDITSYSCALL 25 select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL 26 select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL 27 select HAVE_ARCH_SECCOMP_FILTER 28 select HAVE_ARCH_TRACEHOOK 29 select HAVE_DEBUG_KMEMLEAK 30 select HAVE_DMA_CONTIGUOUS 31 select HAVE_EXIT_THREAD 32 select HAVE_FUNCTION_TRACER 33 select HAVE_FUTEX_CMPXCHG if !MMU 34 select HAVE_HW_BREAKPOINT if PERF_EVENTS 35 select HAVE_IRQ_TIME_ACCOUNTING 36 select HAVE_OPROFILE 37 select HAVE_PCI 38 select HAVE_PERF_EVENTS 39 select HAVE_STACKPROTECTOR 40 select HAVE_SYSCALL_TRACEPOINTS 41 select IRQ_DOMAIN 42 select MODULES_USE_ELF_RELA 43 select PERF_USE_VMALLOC 44 select VIRT_TO_BUS 45 help 46 Xtensa processors are 32-bit RISC machines designed by Tensilica 47 primarily for embedded systems. These processors are both 48 configurable and extensible. The Linux port to the Xtensa 49 architecture supports all processor configurations and extensions, 50 with reasonable minimum requirements. The Xtensa Linux project has 51 a home page at <http://www.linux-xtensa.org/>. 52 53config GENERIC_HWEIGHT 54 def_bool y 55 56config ARCH_HAS_ILOG2_U32 57 def_bool n 58 59config ARCH_HAS_ILOG2_U64 60 def_bool n 61 62config NO_IOPORT_MAP 63 def_bool n 64 65config HZ 66 int 67 default 100 68 69config LOCKDEP_SUPPORT 70 def_bool y 71 72config STACKTRACE_SUPPORT 73 def_bool y 74 75config TRACE_IRQFLAGS_SUPPORT 76 def_bool y 77 78config MMU 79 def_bool n 80 81config HAVE_XTENSA_GPIO32 82 def_bool n 83 84config KASAN_SHADOW_OFFSET 85 hex 86 default 0x6e400000 87 88menu "Processor type and features" 89 90choice 91 prompt "Xtensa Processor Configuration" 92 default XTENSA_VARIANT_FSF 93 94config XTENSA_VARIANT_FSF 95 bool "fsf - default (not generic) configuration" 96 select MMU 97 98config XTENSA_VARIANT_DC232B 99 bool "dc232b - Diamond 232L Standard Core Rev.B (LE)" 100 select MMU 101 select HAVE_XTENSA_GPIO32 102 help 103 This variant refers to Tensilica's Diamond 232L Standard core Rev.B (LE). 104 105config XTENSA_VARIANT_DC233C 106 bool "dc233c - Diamond 233L Standard Core Rev.C (LE)" 107 select MMU 108 select HAVE_XTENSA_GPIO32 109 help 110 This variant refers to Tensilica's Diamond 233L Standard core Rev.C (LE). 111 112config XTENSA_VARIANT_CUSTOM 113 bool "Custom Xtensa processor configuration" 114 select HAVE_XTENSA_GPIO32 115 help 116 Select this variant to use a custom Xtensa processor configuration. 117 You will be prompted for a processor variant CORENAME. 118endchoice 119 120config XTENSA_VARIANT_CUSTOM_NAME 121 string "Xtensa Processor Custom Core Variant Name" 122 depends on XTENSA_VARIANT_CUSTOM 123 help 124 Provide the name of a custom Xtensa processor variant. 125 This CORENAME selects arch/xtensa/variant/CORENAME. 126 Don't forget you have to select MMU if you have one. 127 128config XTENSA_VARIANT_NAME 129 string 130 default "dc232b" if XTENSA_VARIANT_DC232B 131 default "dc233c" if XTENSA_VARIANT_DC233C 132 default "fsf" if XTENSA_VARIANT_FSF 133 default XTENSA_VARIANT_CUSTOM_NAME if XTENSA_VARIANT_CUSTOM 134 135config XTENSA_VARIANT_MMU 136 bool "Core variant has a Full MMU (TLB, Pages, Protection, etc)" 137 depends on XTENSA_VARIANT_CUSTOM 138 default y 139 select MMU 140 help 141 Build a Conventional Kernel with full MMU support, 142 ie: it supports a TLB with auto-loading, page protection. 143 144config XTENSA_VARIANT_HAVE_PERF_EVENTS 145 bool "Core variant has Performance Monitor Module" 146 depends on XTENSA_VARIANT_CUSTOM 147 default n 148 help 149 Enable if core variant has Performance Monitor Module with 150 External Registers Interface. 151 152 If unsure, say N. 153 154config XTENSA_FAKE_NMI 155 bool "Treat PMM IRQ as NMI" 156 depends on XTENSA_VARIANT_HAVE_PERF_EVENTS 157 default n 158 help 159 If PMM IRQ is the only IRQ at EXCM level it is safe to 160 treat it as NMI, which improves accuracy of profiling. 161 162 If there are other interrupts at or above PMM IRQ priority level 163 but not above the EXCM level, PMM IRQ still may be treated as NMI, 164 but only if these IRQs are not used. There will be a build warning 165 saying that this is not safe, and a bugcheck if one of these IRQs 166 actually fire. 167 168 If unsure, say N. 169 170config XTENSA_UNALIGNED_USER 171 bool "Unaligned memory access in user space" 172 help 173 The Xtensa architecture currently does not handle unaligned 174 memory accesses in hardware but through an exception handler. 175 Per default, unaligned memory accesses are disabled in user space. 176 177 Say Y here to enable unaligned memory access in user space. 178 179config HAVE_SMP 180 bool "System Supports SMP (MX)" 181 depends on XTENSA_VARIANT_CUSTOM 182 select XTENSA_MX 183 help 184 This option is used to indicate that the system-on-a-chip (SOC) 185 supports Multiprocessing. Multiprocessor support implemented above 186 the CPU core definition and currently needs to be selected manually. 187 188 Multiprocessor support is implemented with external cache and 189 interrupt controllers. 190 191 The MX interrupt distributer adds Interprocessor Interrupts 192 and causes the IRQ numbers to be increased by 4 for devices 193 like the open cores ethernet driver and the serial interface. 194 195 You still have to select "Enable SMP" to enable SMP on this SOC. 196 197config SMP 198 bool "Enable Symmetric multi-processing support" 199 depends on HAVE_SMP 200 select GENERIC_SMP_IDLE_THREAD 201 help 202 Enabled SMP Software; allows more than one CPU/CORE 203 to be activated during startup. 204 205config NR_CPUS 206 depends on SMP 207 int "Maximum number of CPUs (2-32)" 208 range 2 32 209 default "4" 210 211config HOTPLUG_CPU 212 bool "Enable CPU hotplug support" 213 depends on SMP 214 help 215 Say Y here to allow turning CPUs off and on. CPUs can be 216 controlled through /sys/devices/system/cpu. 217 218 Say N if you want to disable CPU hotplug. 219 220config SECCOMP 221 bool 222 prompt "Enable seccomp to safely compute untrusted bytecode" 223 help 224 This kernel feature is useful for number crunching applications 225 that may need to compute untrusted bytecode during their 226 execution. By using pipes or other transports made available to 227 the process as file descriptors supporting the read/write 228 syscalls, it's possible to isolate those applications in 229 their own address space using seccomp. Once seccomp is 230 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled 231 and the task is only allowed to execute a few safe syscalls 232 defined by each seccomp mode. 233 234config FAST_SYSCALL_XTENSA 235 bool "Enable fast atomic syscalls" 236 default n 237 help 238 fast_syscall_xtensa is a syscall that can make atomic operations 239 on UP kernel when processor has no s32c1i support. 240 241 This syscall is deprecated. It may have issues when called with 242 invalid arguments. It is provided only for backwards compatibility. 243 Only enable it if your userspace software requires it. 244 245 If unsure, say N. 246 247config FAST_SYSCALL_SPILL_REGISTERS 248 bool "Enable spill registers syscall" 249 default n 250 help 251 fast_syscall_spill_registers is a syscall that spills all active 252 register windows of a calling userspace task onto its stack. 253 254 This syscall is deprecated. It may have issues when called with 255 invalid arguments. It is provided only for backwards compatibility. 256 Only enable it if your userspace software requires it. 257 258 If unsure, say N. 259 260config USER_ABI_CALL0 261 bool 262 263choice 264 prompt "Userspace ABI" 265 default USER_ABI_DEFAULT 266 help 267 Select supported userspace ABI. 268 269 If unsure, choose the default ABI. 270 271config USER_ABI_DEFAULT 272 bool "Default ABI only" 273 help 274 Assume default userspace ABI. For XEA2 cores it is windowed ABI. 275 call0 ABI binaries may be run on such kernel, but signal delivery 276 will not work correctly for them. 277 278config USER_ABI_CALL0_ONLY 279 bool "Call0 ABI only" 280 select USER_ABI_CALL0 281 help 282 Select this option to support only call0 ABI in userspace. 283 Windowed ABI binaries will crash with a segfault caused by 284 an illegal instruction exception on the first 'entry' opcode. 285 286 Choose this option if you're planning to run only user code 287 built with call0 ABI. 288 289config USER_ABI_CALL0_PROBE 290 bool "Support both windowed and call0 ABI by probing" 291 select USER_ABI_CALL0 292 help 293 Select this option to support both windowed and call0 userspace 294 ABIs. When enabled all processes are started with PS.WOE disabled 295 and a fast user exception handler for an illegal instruction is 296 used to turn on PS.WOE bit on the first 'entry' opcode executed by 297 the userspace. 298 299 This option should be enabled for the kernel that must support 300 both call0 and windowed ABIs in userspace at the same time. 301 302 Note that Xtensa ISA does not guarantee that entry opcode will 303 raise an illegal instruction exception on cores with XEA2 when 304 PS.WOE is disabled, check whether the target core supports it. 305 306endchoice 307 308endmenu 309 310config XTENSA_CALIBRATE_CCOUNT 311 def_bool n 312 help 313 On some platforms (XT2000, for example), the CPU clock rate can 314 vary. The frequency can be determined, however, by measuring 315 against a well known, fixed frequency, such as an UART oscillator. 316 317config SERIAL_CONSOLE 318 def_bool n 319 320config PLATFORM_HAVE_XIP 321 def_bool n 322 323menu "Platform options" 324 325choice 326 prompt "Xtensa System Type" 327 default XTENSA_PLATFORM_ISS 328 329config XTENSA_PLATFORM_ISS 330 bool "ISS" 331 select XTENSA_CALIBRATE_CCOUNT 332 select SERIAL_CONSOLE 333 help 334 ISS is an acronym for Tensilica's Instruction Set Simulator. 335 336config XTENSA_PLATFORM_XT2000 337 bool "XT2000" 338 select HAVE_IDE 339 help 340 XT2000 is the name of Tensilica's feature-rich emulation platform. 341 This hardware is capable of running a full Linux distribution. 342 343config XTENSA_PLATFORM_XTFPGA 344 bool "XTFPGA" 345 select ETHOC if ETHERNET 346 select PLATFORM_WANT_DEFAULT_MEM if !MMU 347 select SERIAL_CONSOLE 348 select XTENSA_CALIBRATE_CCOUNT 349 select PLATFORM_HAVE_XIP 350 help 351 XTFPGA is the name of Tensilica board family (LX60, LX110, LX200, ML605). 352 This hardware is capable of running a full Linux distribution. 353 354endchoice 355 356config PLATFORM_NR_IRQS 357 int 358 default 3 if XTENSA_PLATFORM_XT2000 359 default 0 360 361config XTENSA_CPU_CLOCK 362 int "CPU clock rate [MHz]" 363 depends on !XTENSA_CALIBRATE_CCOUNT 364 default 16 365 366config GENERIC_CALIBRATE_DELAY 367 bool "Auto calibration of the BogoMIPS value" 368 help 369 The BogoMIPS value can easily be derived from the CPU frequency. 370 371config CMDLINE_BOOL 372 bool "Default bootloader kernel arguments" 373 374config CMDLINE 375 string "Initial kernel command string" 376 depends on CMDLINE_BOOL 377 default "console=ttyS0,38400 root=/dev/ram" 378 help 379 On some architectures (EBSA110 and CATS), there is currently no way 380 for the boot loader to pass arguments to the kernel. For these 381 architectures, you should supply some command-line options at build 382 time by entering them here. As a minimum, you should specify the 383 memory size and the root device (e.g., mem=64M root=/dev/nfs). 384 385config USE_OF 386 bool "Flattened Device Tree support" 387 select OF 388 select OF_EARLY_FLATTREE 389 help 390 Include support for flattened device tree machine descriptions. 391 392config BUILTIN_DTB_SOURCE 393 string "DTB to build into the kernel image" 394 depends on OF 395 396config PARSE_BOOTPARAM 397 bool "Parse bootparam block" 398 default y 399 help 400 Parse parameters passed to the kernel from the bootloader. It may 401 be disabled if the kernel is known to run without the bootloader. 402 403 If unsure, say Y. 404 405config BLK_DEV_SIMDISK 406 tristate "Host file-based simulated block device support" 407 default n 408 depends on XTENSA_PLATFORM_ISS && BLOCK 409 help 410 Create block devices that map to files in the host file system. 411 Device binding to host file may be changed at runtime via proc 412 interface provided the device is not in use. 413 414config BLK_DEV_SIMDISK_COUNT 415 int "Number of host file-based simulated block devices" 416 range 1 10 417 depends on BLK_DEV_SIMDISK 418 default 2 419 help 420 This is the default minimal number of created block devices. 421 Kernel/module parameter 'simdisk_count' may be used to change this 422 value at runtime. More file names (but no more than 10) may be 423 specified as parameters, simdisk_count grows accordingly. 424 425config SIMDISK0_FILENAME 426 string "Host filename for the first simulated device" 427 depends on BLK_DEV_SIMDISK = y 428 default "" 429 help 430 Attach a first simdisk to a host file. Conventionally, this file 431 contains a root file system. 432 433config SIMDISK1_FILENAME 434 string "Host filename for the second simulated device" 435 depends on BLK_DEV_SIMDISK = y && BLK_DEV_SIMDISK_COUNT != 1 436 default "" 437 help 438 Another simulated disk in a host file for a buildroot-independent 439 storage. 440 441config XTFPGA_LCD 442 bool "Enable XTFPGA LCD driver" 443 depends on XTENSA_PLATFORM_XTFPGA 444 default n 445 help 446 There's a 2x16 LCD on most of XTFPGA boards, kernel may output 447 progress messages there during bootup/shutdown. It may be useful 448 during board bringup. 449 450 If unsure, say N. 451 452config XTFPGA_LCD_BASE_ADDR 453 hex "XTFPGA LCD base address" 454 depends on XTFPGA_LCD 455 default "0x0d0c0000" 456 help 457 Base address of the LCD controller inside KIO region. 458 Different boards from XTFPGA family have LCD controller at different 459 addresses. Please consult prototyping user guide for your board for 460 the correct address. Wrong address here may lead to hardware lockup. 461 462config XTFPGA_LCD_8BIT_ACCESS 463 bool "Use 8-bit access to XTFPGA LCD" 464 depends on XTFPGA_LCD 465 default n 466 help 467 LCD may be connected with 4- or 8-bit interface, 8-bit access may 468 only be used with 8-bit interface. Please consult prototyping user 469 guide for your board for the correct interface width. 470 471comment "Kernel memory layout" 472 473config INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX 474 bool "Initialize Xtensa MMU inside the Linux kernel code" 475 depends on !XTENSA_VARIANT_FSF && !XTENSA_VARIANT_DC232B 476 default y if XTENSA_VARIANT_DC233C || XTENSA_VARIANT_CUSTOM 477 help 478 Earlier version initialized the MMU in the exception vector 479 before jumping to _startup in head.S and had an advantage that 480 it was possible to place a software breakpoint at 'reset' and 481 then enter your normal kernel breakpoints once the MMU was mapped 482 to the kernel mappings (0XC0000000). 483 484 This unfortunately won't work for U-Boot and likely also wont 485 work for using KEXEC to have a hot kernel ready for doing a 486 KDUMP. 487 488 So now the MMU is initialized in head.S but it's necessary to 489 use hardware breakpoints (gdb 'hbreak' cmd) to break at _startup. 490 xt-gdb can't place a Software Breakpoint in the 0XD region prior 491 to mapping the MMU and after mapping even if the area of low memory 492 was mapped gdb wouldn't remove the breakpoint on hitting it as the 493 PC wouldn't match. Since Hardware Breakpoints are recommended for 494 Linux configurations it seems reasonable to just assume they exist 495 and leave this older mechanism for unfortunate souls that choose 496 not to follow Tensilica's recommendation. 497 498 Selecting this will cause U-Boot to set the KERNEL Load and Entry 499 address at 0x00003000 instead of the mapped std of 0xD0003000. 500 501 If in doubt, say Y. 502 503config XIP_KERNEL 504 bool "Kernel Execute-In-Place from ROM" 505 depends on PLATFORM_HAVE_XIP 506 help 507 Execute-In-Place allows the kernel to run from non-volatile storage 508 directly addressable by the CPU, such as NOR flash. This saves RAM 509 space since the text section of the kernel is not loaded from flash 510 to RAM. Read-write sections, such as the data section and stack, 511 are still copied to RAM. The XIP kernel is not compressed since 512 it has to run directly from flash, so it will take more space to 513 store it. The flash address used to link the kernel object files, 514 and for storing it, is configuration dependent. Therefore, if you 515 say Y here, you must know the proper physical address where to 516 store the kernel image depending on your own flash memory usage. 517 518 Also note that the make target becomes "make xipImage" rather than 519 "make Image" or "make uImage". The final kernel binary to put in 520 ROM memory will be arch/xtensa/boot/xipImage. 521 522 If unsure, say N. 523 524config MEMMAP_CACHEATTR 525 hex "Cache attributes for the memory address space" 526 depends on !MMU 527 default 0x22222222 528 help 529 These cache attributes are set up for noMMU systems. Each hex digit 530 specifies cache attributes for the corresponding 512MB memory 531 region: bits 0..3 -- for addresses 0x00000000..0x1fffffff, 532 bits 4..7 -- for addresses 0x20000000..0x3fffffff, and so on. 533 534 Cache attribute values are specific for the MMU type. 535 For region protection MMUs: 536 1: WT cached, 537 2: cache bypass, 538 4: WB cached, 539 f: illegal. 540 For ful MMU: 541 bit 0: executable, 542 bit 1: writable, 543 bits 2..3: 544 0: cache bypass, 545 1: WB cache, 546 2: WT cache, 547 3: special (c and e are illegal, f is reserved). 548 For MPU: 549 0: illegal, 550 1: WB cache, 551 2: WB, no-write-allocate cache, 552 3: WT cache, 553 4: cache bypass. 554 555config KSEG_PADDR 556 hex "Physical address of the KSEG mapping" 557 depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX && MMU 558 default 0x00000000 559 help 560 This is the physical address where KSEG is mapped. Please refer to 561 the chosen KSEG layout help for the required address alignment. 562 Unpacked kernel image (including vectors) must be located completely 563 within KSEG. 564 Physical memory below this address is not available to linux. 565 566 If unsure, leave the default value here. 567 568config KERNEL_VIRTUAL_ADDRESS 569 hex "Kernel virtual address" 570 depends on MMU && XIP_KERNEL 571 default 0xd0003000 572 help 573 This is the virtual address where the XIP kernel is mapped. 574 XIP kernel may be mapped into KSEG or KIO region, virtual address 575 provided here must match kernel load address provided in 576 KERNEL_LOAD_ADDRESS. 577 578config KERNEL_LOAD_ADDRESS 579 hex "Kernel load address" 580 default 0x60003000 if !MMU 581 default 0x00003000 if MMU && INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX 582 default 0xd0003000 if MMU && !INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX 583 help 584 This is the address where the kernel is loaded. 585 It is virtual address for MMUv2 configurations and physical address 586 for all other configurations. 587 588 If unsure, leave the default value here. 589 590choice 591 prompt "Relocatable vectors location" 592 default XTENSA_VECTORS_IN_TEXT 593 help 594 Choose whether relocatable vectors are merged into the kernel .text 595 or placed separately at runtime. This option does not affect 596 configurations without VECBASE register where vectors are always 597 placed at their hardware-defined locations. 598 599config XTENSA_VECTORS_IN_TEXT 600 bool "Merge relocatable vectors into kernel text" 601 depends on !MTD_XIP 602 help 603 This option puts relocatable vectors into the kernel .text section 604 with proper alignment. 605 This is a safe choice for most configurations. 606 607config XTENSA_VECTORS_SEPARATE 608 bool "Put relocatable vectors at fixed address" 609 help 610 This option puts relocatable vectors at specific virtual address. 611 Vectors are merged with the .init data in the kernel image and 612 are copied into their designated location during kernel startup. 613 Use it to put vectors into IRAM or out of FLASH on kernels with 614 XIP-aware MTD support. 615 616endchoice 617 618config VECTORS_ADDR 619 hex "Kernel vectors virtual address" 620 default 0x00000000 621 depends on XTENSA_VECTORS_SEPARATE 622 help 623 This is the virtual address of the (relocatable) vectors base. 624 It must be within KSEG if MMU is used. 625 626config XIP_DATA_ADDR 627 hex "XIP kernel data virtual address" 628 depends on XIP_KERNEL 629 default 0x00000000 630 help 631 This is the virtual address where XIP kernel data is copied. 632 It must be within KSEG if MMU is used. 633 634config PLATFORM_WANT_DEFAULT_MEM 635 def_bool n 636 637config DEFAULT_MEM_START 638 hex 639 prompt "PAGE_OFFSET/PHYS_OFFSET" if !MMU && PLATFORM_WANT_DEFAULT_MEM 640 default 0x60000000 if PLATFORM_WANT_DEFAULT_MEM 641 default 0x00000000 642 help 643 This is the base address used for both PAGE_OFFSET and PHYS_OFFSET 644 in noMMU configurations. 645 646 If unsure, leave the default value here. 647 648choice 649 prompt "KSEG layout" 650 depends on MMU 651 default XTENSA_KSEG_MMU_V2 652 653config XTENSA_KSEG_MMU_V2 654 bool "MMUv2: 128MB cached + 128MB uncached" 655 help 656 MMUv2 compatible kernel memory map: TLB way 5 maps 128MB starting 657 at KSEG_PADDR to 0xd0000000 with cache and to 0xd8000000 658 without cache. 659 KSEG_PADDR must be aligned to 128MB. 660 661config XTENSA_KSEG_256M 662 bool "256MB cached + 256MB uncached" 663 depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX 664 help 665 TLB way 6 maps 256MB starting at KSEG_PADDR to 0xb0000000 666 with cache and to 0xc0000000 without cache. 667 KSEG_PADDR must be aligned to 256MB. 668 669config XTENSA_KSEG_512M 670 bool "512MB cached + 512MB uncached" 671 depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX 672 help 673 TLB way 6 maps 512MB starting at KSEG_PADDR to 0xa0000000 674 with cache and to 0xc0000000 without cache. 675 KSEG_PADDR must be aligned to 256MB. 676 677endchoice 678 679config HIGHMEM 680 bool "High Memory Support" 681 depends on MMU 682 help 683 Linux can use the full amount of RAM in the system by 684 default. However, the default MMUv2 setup only maps the 685 lowermost 128 MB of memory linearly to the areas starting 686 at 0xd0000000 (cached) and 0xd8000000 (uncached). 687 When there are more than 128 MB memory in the system not 688 all of it can be "permanently mapped" by the kernel. 689 The physical memory that's not permanently mapped is called 690 "high memory". 691 692 If you are compiling a kernel which will never run on a 693 machine with more than 128 MB total physical RAM, answer 694 N here. 695 696 If unsure, say Y. 697 698config FORCE_MAX_ZONEORDER 699 int "Maximum zone order" 700 default "11" 701 help 702 The kernel memory allocator divides physically contiguous memory 703 blocks into "zones", where each zone is a power of two number of 704 pages. This option selects the largest power of two that the kernel 705 keeps in the memory allocator. If you need to allocate very large 706 blocks of physically contiguous memory, then you may need to 707 increase this value. 708 709 This config option is actually maximum order plus one. For example, 710 a value of 11 means that the largest free memory block is 2^10 pages. 711 712endmenu 713 714menu "Power management options" 715 716source "kernel/power/Kconfig" 717 718endmenu 719