arch/powerpc/Kconfig

   1 # For a description of the syntax of this configuration file,
   2 # see Documentation/kbuild/kconfig-language.txt.
   3 #
   4
   5 mainmenu "Linux/PowerPC Kernel Configuration"
   6
   7 source "arch/powerpc/platforms/Kconfig.cputype"
   8
   9 config PPC32
  10         bool
  11         default y if !PPC64
  12
  13 config 64BIT
  14         bool
  15         default y if PPC64
  16
  17 config WORD_SIZE
  18         int
  19         default 64 if PPC64
  20         default 32 if !PPC64
  21
  22 config ARCH_PHYS_ADDR_T_64BIT
  23        def_bool PPC64 || PHYS_64BIT
  24
  25 config MMU
  26         bool
  27         default y
  28
  29 config GENERIC_CMOS_UPDATE
  30         def_bool y
  31
  32 config GENERIC_TIME
  33         def_bool y
  34
  35 config GENERIC_TIME_VSYSCALL
  36         def_bool y
  37
  38 config GENERIC_CLOCKEVENTS
  39         def_bool y
  40
  41 config GENERIC_HARDIRQS
  42         bool
  43         default y
  44
  45 config GENERIC_HARDIRQS_NO__DO_IRQ
  46         bool
  47         default y
  48
  49 config HAVE_SETUP_PER_CPU_AREA
  50         def_bool PPC64
  51
  52 config IRQ_PER_CPU
  53         bool
  54         default y
  55
  56 config STACKTRACE_SUPPORT
  57         bool
  58         default y
  59
  60 config HAVE_LATENCYTOP_SUPPORT
  61         def_bool y
  62
  63 config TRACE_IRQFLAGS_SUPPORT
  64         bool
  65         depends on PPC64
  66         default y
  67
  68 config LOCKDEP_SUPPORT
  69         bool
  70         default y
  71
  72 config RWSEM_GENERIC_SPINLOCK
  73         bool
  74
  75 config RWSEM_XCHGADD_ALGORITHM
  76         bool
  77         default y
  78
  79 config GENERIC_LOCKBREAK
  80         bool
  81         default y
  82         depends on SMP && PREEMPT
  83
  84 config ARCH_HAS_ILOG2_U32
  85         bool
  86         default y
  87
  88 config ARCH_HAS_ILOG2_U64
  89         bool
  90         default y if 64BIT
  91
  92 config GENERIC_HWEIGHT
  93         bool
  94         default y
  95
  96 config GENERIC_CALIBRATE_DELAY
  97         bool
  98         default y
  99
 100 config GENERIC_FIND_NEXT_BIT
 101         bool
 102         default y
 103
 104 config GENERIC_GPIO
 105         bool
 106         help
 107           Generic GPIO API support
 108
 109 config ARCH_NO_VIRT_TO_BUS
 110         def_bool PPC64
 111
 112 config PPC
 113         bool
 114         default y
 115         select HAVE_FTRACE_MCOUNT_RECORD
 116         select HAVE_DYNAMIC_FTRACE
 117         select HAVE_FUNCTION_TRACER
 118         select HAVE_FUNCTION_GRAPH_TRACER
 119         select ARCH_WANT_OPTIONAL_GPIOLIB
 120         select HAVE_IDE
 121         select HAVE_IOREMAP_PROT
 122         select HAVE_EFFICIENT_UNALIGNED_ACCESS
 123         select HAVE_KPROBES
 124         select HAVE_ARCH_KGDB
 125         select HAVE_KRETPROBES
 126         select HAVE_ARCH_TRACEHOOK
 127         select HAVE_LMB
 128         select HAVE_DMA_ATTRS if PPC64
 129         select USE_GENERIC_SMP_HELPERS if SMP
 130         select HAVE_OPROFILE
 131         select HAVE_SYSCALL_WRAPPERS if PPC64
 132
 133 config EARLY_PRINTK
 134         bool
 135         default y
 136
 137 config COMPAT
 138         bool
 139         default y if PPC64
 140         select COMPAT_BINFMT_ELF
 141
 142 config SYSVIPC_COMPAT
 143         bool
 144         depends on COMPAT && SYSVIPC
 145         default y
 146
 147 # All PPC32s use generic nvram driver through ppc_md
 148 config GENERIC_NVRAM
 149         bool
 150         default y if PPC32
 151
 152 config SCHED_OMIT_FRAME_POINTER
 153         bool
 154         default y
 155
 156 config ARCH_MAY_HAVE_PC_FDC
 157         bool
 158         default !PPC_PSERIES || PCI
 159
 160 config PPC_OF
 161         def_bool y
 162
 163 config OF
 164         def_bool y
 165
 166 config PPC_UDBG_16550
 167         bool
 168         default n
 169
 170 config GENERIC_TBSYNC
 171         bool
 172         default y if PPC32 && SMP
 173         default n
 174
 175 config AUDIT_ARCH
 176         bool
 177         default y
 178
 179 config GENERIC_BUG
 180         bool
 181         default y
 182         depends on BUG
 183
 184 config SYS_SUPPORTS_APM_EMULATION
 185         default y if PMAC_APM_EMU
 186         bool
 187
 188 config DTC
 189        bool
 190        default y
 191
 192 config DEFAULT_UIMAGE
 193         bool
 194         help
 195           Used to allow a board to specify it wants a uImage built by default
 196         default n
 197
 198 config REDBOOT
 199         bool
 200
 201 config HIBERNATE_32
 202         bool
 203         depends on (PPC_PMAC && !SMP) || BROKEN
 204         default y
 205
 206 config HIBERNATE_64
 207         bool
 208         depends on BROKEN || (PPC_PMAC64 && EXPERIMENTAL)
 209         default y
 210
 211 config ARCH_HIBERNATION_POSSIBLE
 212         bool
 213         depends on (PPC64 && HIBERNATE_64) || (PPC32 && HIBERNATE_32)
 214         default y
 215
 216 config ARCH_SUSPEND_POSSIBLE
 217         def_bool y
 218         depends on ADB_PMU || PPC_EFIKA || PPC_LITE5200 || PPC_83xx
 219
 220 config PPC_DCR_NATIVE
 221         bool
 222         default n
 223
 224 config PPC_DCR_MMIO
 225         bool
 226         default n
 227
 228 config PPC_DCR
 229         bool
 230         depends on PPC_DCR_NATIVE || PPC_DCR_MMIO
 231         default y
 232
 233 config PPC_OF_PLATFORM_PCI
 234         bool
 235         depends on PCI
 236         depends on PPC64 # not supported on 32 bits yet
 237         default n
 238
 239 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
 240         def_bool y
 241
 242 source "init/Kconfig"
 243
 244 source "kernel/Kconfig.freezer"
 245
 246 source "arch/powerpc/sysdev/Kconfig"
 247 source "arch/powerpc/platforms/Kconfig"
 248
 249 menu "Kernel options"
 250
 251 config HIGHMEM
 252         bool "High memory support"
 253         depends on PPC32
 254
 255 source kernel/time/Kconfig
 256 source kernel/Kconfig.hz
 257 source kernel/Kconfig.preempt
 258 source "fs/Kconfig.binfmt"
 259
 260 config HUGETLB_PAGE_SIZE_VARIABLE
 261         bool
 262         depends on HUGETLB_PAGE
 263         default y
 264
 265 config MATH_EMULATION
 266         bool "Math emulation"
 267         depends on 4xx || 8xx || E200 || PPC_MPC832x || E500
 268         ---help---
 269           Some PowerPC chips designed for embedded applications do not have
 270           a floating-point unit and therefore do not implement the
 271           floating-point instructions in the PowerPC instruction set.  If you
 272           say Y here, the kernel will include code to emulate a floating-point
 273           unit, which will allow programs that use floating-point
 274           instructions to run.
 275
 276 config 8XX_MINIMAL_FPEMU
 277         bool "Minimal math emulation for 8xx"
 278         depends on 8xx && !MATH_EMULATION
 279         help
 280           Older arch/ppc kernels still emulated a few floating point
 281           instructions such as load and store, even when full math
 282           emulation is disabled.  Say "Y" here if you want to preserve
 283           this behavior.
 284
 285           It is recommended that you build a soft-float userspace instead.
 286
 287 config IOMMU_VMERGE
 288         bool "Enable IOMMU virtual merging"
 289         depends on PPC64
 290         default y
 291         help
 292           Cause IO segments sent to a device for DMA to be merged virtually
 293           by the IOMMU when they happen to have been allocated contiguously.
 294           This doesn't add pressure to the IOMMU allocator. However, some
 295           drivers don't support getting large merged segments coming back
 296           from *_map_sg().
 297
 298           Most drivers don't have this problem; it is safe to say Y here.
 299
 300 config IOMMU_HELPER
 301         def_bool PPC64
 302
 303 config PPC_NEED_DMA_SYNC_OPS
 304         def_bool y
 305         depends on NOT_COHERENT_CACHE
 306
 307 config HOTPLUG_CPU
 308         bool "Support for enabling/disabling CPUs"
 309         depends on SMP && HOTPLUG && EXPERIMENTAL && (PPC_PSERIES || PPC_PMAC)
 310         ---help---
 311           Say Y here to be able to disable and re-enable individual
 312           CPUs at runtime on SMP machines.
 313
 314           Say N if you are unsure.
 315
 316 config ARCH_ENABLE_MEMORY_HOTPLUG
 317         def_bool y
 318
 319 config ARCH_HAS_WALK_MEMORY
 320         def_bool y
 321
 322 config ARCH_ENABLE_MEMORY_HOTREMOVE
 323         def_bool y
 324
 325 config KEXEC
 326         bool "kexec system call (EXPERIMENTAL)"
 327         depends on PPC_BOOK3S && EXPERIMENTAL
 328         help
 329           kexec is a system call that implements the ability to shutdown your
 330           current kernel, and to start another kernel.  It is like a reboot
 331           but it is independent of the system firmware.   And like a reboot
 332           you can start any kernel with it, not just Linux.
 333
 334           The name comes from the similarity to the exec system call.
 335
 336           It is an ongoing process to be certain the hardware in a machine
 337           is properly shutdown, so do not be surprised if this code does not
 338           initially work for you.  It may help to enable device hotplugging
 339           support.  As of this writing the exact hardware interface is
 340           strongly in flux, so no good recommendation can be made.
 341
 342 config CRASH_DUMP
 343         bool "Build a kdump crash kernel"
 344         depends on PPC64 || 6xx
 345         select RELOCATABLE if PPC64
 346         help
 347           Build a kernel suitable for use as a kdump capture kernel.
 348           The same kernel binary can be used as production kernel and dump
 349           capture kernel.
 350
 351 config PHYP_DUMP
 352         bool "Hypervisor-assisted dump (EXPERIMENTAL)"
 353         depends on PPC_PSERIES && EXPERIMENTAL
 354         help
 355           Hypervisor-assisted dump is meant to be a kdump replacement
 356           offering robustness and speed not possible without system
 357           hypervisor assistance.
 358
 359           If unsure, say "N"
 360
 361 config PPCBUG_NVRAM
 362         bool "Enable reading PPCBUG NVRAM during boot" if PPLUS || LOPEC
 363         default y if PPC_PREP
 364
 365 config IRQ_ALL_CPUS
 366         bool "Distribute interrupts on all CPUs by default"
 367         depends on SMP && !MV64360
 368         help
 369           This option gives the kernel permission to distribute IRQs across
 370           multiple CPUs.  Saying N here will route all IRQs to the first
 371           CPU.  Generally saying Y is safe, although some problems have been
 372           reported with SMP Power Macintoshes with this option enabled.
 373
 374 config NUMA
 375         bool "NUMA support"
 376         depends on PPC64
 377         default y if SMP && PPC_PSERIES
 378
 379 config NODES_SHIFT
 380         int
 381         default "4"
 382         depends on NEED_MULTIPLE_NODES
 383
 384 config ARCH_SELECT_MEMORY_MODEL
 385         def_bool y
 386         depends on PPC64
 387
 388 config ARCH_FLATMEM_ENABLE
 389         def_bool y
 390         depends on (PPC64 && !NUMA) || PPC32
 391
 392 config ARCH_SPARSEMEM_ENABLE
 393         def_bool y
 394         depends on PPC64
 395         select SPARSEMEM_VMEMMAP_ENABLE
 396
 397 config ARCH_SPARSEMEM_DEFAULT
 398         def_bool y
 399         depends on (SMP && PPC_PSERIES) || PPC_PS3
 400
 401 config ARCH_POPULATES_NODE_MAP
 402         def_bool y
 403
 404 source "mm/Kconfig"
 405
 406 config ARCH_MEMORY_PROBE
 407         def_bool y
 408         depends on MEMORY_HOTPLUG
 409
 410 # Some NUMA nodes have memory ranges that span
 411 # other nodes.  Even though a pfn is valid and
 412 # between a node's start and end pfns, it may not
 413 # reside on that node.  See memmap_init_zone()
 414 # for details.
 415 config NODES_SPAN_OTHER_NODES
 416         def_bool y
 417         depends on NEED_MULTIPLE_NODES
 418
 419 config PPC_HAS_HASH_64K
 420         bool
 421         depends on PPC64
 422         default n
 423
 424 config STDBINUTILS
 425         bool "Using standard binutils settings"
 426         depends on 44x
 427         default y
 428         help
 429           Turning this option off allows you to select 256KB PAGE_SIZE on 44x.
 430           Note, that kernel will be able to run only those applications,
 431           which had been compiled using binutils later than 2.17.50.0.3 with
 432           '-zmax-page-size' set to 256K (the default is 64K). Or, if using
 433           the older binutils, you can patch them with a trivial patch, which
 434           changes the ELF_MAXPAGESIZE definition from 0x10000 to 0x40000.
 435
 436 choice
 437         prompt "Page size"
 438         default PPC_4K_PAGES
 439         help
 440           Select the kernel logical page size. Increasing the page size
 441           will reduce software overhead at each page boundary, allow
 442           hardware prefetch mechanisms to be more effective, and allow
 443           larger dma transfers increasing IO efficiency and reducing
 444           overhead. However the utilization of memory will increase.
 445           For example, each cached file will using a multiple of the
 446           page size to hold its contents and the difference between the
 447           end of file and the end of page is wasted.
 448
 449           Some dedicated systems, such as software raid serving with
 450           accelerated calculations, have shown significant increases.
 451
 452           If you configure a 64 bit kernel for 64k pages but the
 453           processor does not support them, then the kernel will simulate
 454           them with 4k pages, loading them on demand, but with the
 455           reduced software overhead and larger internal fragmentation.
 456           For the 32 bit kernel, a large page option will not be offered
 457           unless it is supported by the configured processor.
 458
 459           If unsure, choose 4K_PAGES.
 460
 461 config PPC_4K_PAGES
 462         bool "4k page size"
 463
 464 config PPC_16K_PAGES
 465         bool "16k page size" if 44x
 466
 467 config PPC_64K_PAGES
 468         bool "64k page size" if 44x || PPC_STD_MMU_64
 469         select PPC_HAS_HASH_64K if PPC_STD_MMU_64
 470
 471 config PPC_256K_PAGES
 472         bool "256k page size" if 44x
 473         depends on !STDBINUTILS
 474         help
 475           Make the page size 256k.
 476
 477           As the ELF standard only requires alignment to support page
 478           sizes up to 64k, you will need to compile all of your user
 479           space applications with a non-standard binutils settings
 480           (see the STDBINUTILS description for details).
 481
 482           Say N unless you know what you are doing.
 483
 484 endchoice
 485
 486 config FORCE_MAX_ZONEORDER
 487         int "Maximum zone order"
 488         range 9 64 if PPC_STD_MMU_64 && PPC_64K_PAGES
 489         default "9" if PPC_STD_MMU_64 && PPC_64K_PAGES
 490         range 13 64 if PPC_STD_MMU_64 && !PPC_64K_PAGES
 491         default "13" if PPC_STD_MMU_64 && !PPC_64K_PAGES
 492         range 9 64 if PPC_STD_MMU_32 && PPC_16K_PAGES
 493         default "9" if PPC_STD_MMU_32 && PPC_16K_PAGES
 494         range 7 64 if PPC_STD_MMU_32 && PPC_64K_PAGES
 495         default "7" if PPC_STD_MMU_32 && PPC_64K_PAGES
 496         range 5 64 if PPC_STD_MMU_32 && PPC_256K_PAGES
 497         default "5" if PPC_STD_MMU_32 && PPC_256K_PAGES
 498         range 11 64
 499         default "11"
 500         help
 501           The kernel memory allocator divides physically contiguous memory
 502           blocks into "zones", where each zone is a power of two number of
 503           pages.  This option selects the largest power of two that the kernel
 504           keeps in the memory allocator.  If you need to allocate very large
 505           blocks of physically contiguous memory, then you may need to
 506           increase this value.
 507
 508           This config option is actually maximum order plus one. For example,
 509           a value of 11 means that the largest free memory block is 2^10 pages.
 510
 511           The page size is not necessarily 4KB.  For example, on 64-bit
 512           systems, 64KB pages can be enabled via CONFIG_PPC_64K_PAGES.  Keep
 513           this in mind when choosing a value for this option.
 514
 515 config PPC_SUBPAGE_PROT
 516         bool "Support setting protections for 4k subpages"
 517         depends on PPC_STD_MMU_64 && PPC_64K_PAGES
 518         help
 519           This option adds support for a system call to allow user programs
 520           to set access permissions (read/write, readonly, or no access)
 521           on the 4k subpages of each 64k page.
 522
 523 config SCHED_SMT
 524         bool "SMT (Hyperthreading) scheduler support"
 525         depends on PPC64 && SMP
 526         help
 527           SMT scheduler support improves the CPU scheduler's decision making
 528           when dealing with POWER5 cpus at a cost of slightly increased
 529           overhead in some places. If unsure say N here.
 530
 531 config PROC_DEVICETREE
 532         bool "Support for device tree in /proc"
 533         depends on PROC_FS
 534         help
 535           This option adds a device-tree directory under /proc which contains
 536           an image of the device tree that the kernel copies from Open
 537           Firmware or other boot firmware. If unsure, say Y here.
 538
 539 config CMDLINE_BOOL
 540         bool "Default bootloader kernel arguments"
 541
 542 config CMDLINE
 543         string "Initial kernel command string"
 544         depends on CMDLINE_BOOL
 545         default "console=ttyS0,9600 console=tty0 root=/dev/sda2"
 546         help
 547           On some platforms, there is currently no way for the boot loader to
 548           pass arguments to the kernel. For these platforms, you can supply
 549           some command-line options at build time by entering them here.  In
 550           most cases you will need to specify the root device here.
 551
 552 config EXTRA_TARGETS
 553         string "Additional default image types"
 554         help
 555           List additional targets to be built by the bootwrapper here (separated
 556           by spaces).  This is useful for targets that depend of device tree
 557           files in the .dts directory.
 558
 559           Targets in this list will be build as part of the default build
 560           target, or when the user does a 'make zImage' or a
 561           'make zImage.initrd'.
 562
 563           If unsure, leave blank
 564
 565 if !44x || BROKEN
 566 config ARCH_WANTS_FREEZER_CONTROL
 567         def_bool y
 568         depends on ADB_PMU
 569
 570 source kernel/power/Kconfig
 571 endif
 572
 573 config SECCOMP
 574         bool "Enable seccomp to safely compute untrusted bytecode"
 575         depends on PROC_FS
 576         default y
 577         help
 578           This kernel feature is useful for number crunching applications
 579           that may need to compute untrusted bytecode during their
 580           execution. By using pipes or other transports made available to
 581           the process as file descriptors supporting the read/write
 582           syscalls, it's possible to isolate those applications in
 583           their own address space using seccomp. Once seccomp is
 584           enabled via /proc/<pid>/seccomp, it cannot be disabled
 585           and the task is only allowed to execute a few safe syscalls
 586           defined by each seccomp mode.
 587
 588           If unsure, say Y. Only embedded should say N here.
 589
 590 endmenu
 591
 592 config ISA_DMA_API
 593         bool
 594         default !PPC_ISERIES || PCI
 595
 596 menu "Bus options"
 597
 598 config ISA
 599         bool "Support for ISA-bus hardware"
 600         depends on PPC_PREP || PPC_CHRP
 601         select PPC_I8259
 602         help
 603           Find out whether you have ISA slots on your motherboard.  ISA is the
 604           name of a bus system, i.e. the way the CPU talks to the other stuff
 605           inside your box.  If you have an Apple machine, say N here; if you
 606           have an IBM RS/6000 or pSeries machine or a PReP machine, say Y.  If
 607           you have an embedded board, consult your board documentation.
 608
 609 config ZONE_DMA
 610         bool
 611         default y
 612
 613 config GENERIC_ISA_DMA
 614         bool
 615         depends on PPC64 || POWER4 || 6xx && !CPM2
 616         default y
 617
 618 config PPC_INDIRECT_PCI
 619         bool
 620         depends on PCI
 621         default y if 40x || 44x
 622         default n
 623
 624 config EISA
 625         bool
 626
 627 config SBUS
 628         bool
 629
 630 config FSL_SOC
 631         bool
 632
 633 config FSL_PCI
 634         bool
 635         select PPC_INDIRECT_PCI
 636         select PCI_QUIRKS
 637
 638 config 4xx_SOC
 639         bool
 640
 641 config FSL_LBC
 642         bool
 643         help
 644           Freescale Localbus support
 645
 646 config FSL_GTM
 647         bool
 648         depends on PPC_83xx || QUICC_ENGINE || CPM2
 649         help
 650           Freescale General-purpose Timers support
 651
 652 # Yes MCA RS/6000s exist but Linux-PPC does not currently support any
 653 config MCA
 654         bool
 655
 656 # Platforms that what PCI turned unconditionally just do select PCI
 657 # in their config node.  Platforms that want to choose at config
 658 # time should select PPC_PCI_CHOICE
 659 config PPC_PCI_CHOICE
 660         bool
 661
 662 config PCI
 663         bool "PCI support" if PPC_PCI_CHOICE
 664         default y if !40x && !CPM2 && !8xx && !PPC_83xx \
 665                 && !PPC_85xx && !PPC_86xx
 666         default PCI_PERMEDIA if !4xx && !CPM2 && !8xx
 667         default PCI_QSPAN if !4xx && !CPM2 && 8xx
 668         select ARCH_SUPPORTS_MSI
 669         help
 670           Find out whether your system includes a PCI bus. PCI is the name of
 671           a bus system, i.e. the way the CPU talks to the other stuff inside
 672           your box.  If you say Y here, the kernel will include drivers and
 673           infrastructure code to support PCI bus devices.
 674
 675 config PCI_DOMAINS
 676         def_bool PCI
 677
 678 config PCI_SYSCALL
 679         def_bool PCI
 680
 681 config PCI_QSPAN
 682         bool "QSpan PCI"
 683         depends on !4xx && !CPM2 && 8xx
 684         select PPC_I8259
 685         help
 686           Say Y here if you have a system based on a Motorola 8xx-series
 687           embedded processor with a QSPAN PCI interface, otherwise say N.
 688
 689 config PCI_8260
 690         bool
 691         depends on PCI && 8260
 692         select PPC_INDIRECT_PCI
 693         default y
 694
 695 config 8260_PCI9
 696         bool "Enable workaround for MPC826x erratum PCI 9"
 697         depends on PCI_8260 && !8272
 698         default y
 699
 700 choice
 701         prompt "IDMA channel for PCI 9 workaround"
 702         depends on 8260_PCI9
 703
 704 config 8260_PCI9_IDMA1
 705         bool "IDMA1"
 706
 707 config 8260_PCI9_IDMA2
 708         bool "IDMA2"
 709
 710 config 8260_PCI9_IDMA3
 711         bool "IDMA3"
 712
 713 config 8260_PCI9_IDMA4
 714         bool "IDMA4"
 715
 716 endchoice
 717
 718 source "drivers/pci/pcie/Kconfig"
 719
 720 source "drivers/pci/Kconfig"
 721
 722 source "drivers/pcmcia/Kconfig"
 723
 724 source "drivers/pci/hotplug/Kconfig"
 725
 726 config HAS_RAPIDIO
 727         bool
 728         default n
 729
 730 config RAPIDIO
 731         bool "RapidIO support"
 732         depends on HAS_RAPIDIO
 733         help
 734           If you say Y here, the kernel will include drivers and
 735           infrastructure code to support RapidIO interconnect devices.
 736
 737 source "drivers/rapidio/Kconfig"
 738
 739 endmenu
 740
 741 menu "Advanced setup"
 742         depends on PPC32
 743
 744 config ADVANCED_OPTIONS
 745         bool "Prompt for advanced kernel configuration options"
 746         help
 747           This option will enable prompting for a variety of advanced kernel
 748           configuration options.  These options can cause the kernel to not
 749           work if they are set incorrectly, but can be used to optimize certain
 750           aspects of kernel memory management.
 751
 752           Unless you know what you are doing, say N here.
 753
 754 comment "Default settings for advanced configuration options are used"
 755         depends on !ADVANCED_OPTIONS
 756
 757 config LOWMEM_SIZE_BOOL
 758         bool "Set maximum low memory"
 759         depends on ADVANCED_OPTIONS
 760         help
 761           This option allows you to set the maximum amount of memory which
 762           will be used as "low memory", that is, memory which the kernel can
 763           access directly, without having to set up a kernel virtual mapping.
 764           This can be useful in optimizing the layout of kernel virtual
 765           memory.
 766
 767           Say N here unless you know what you are doing.
 768
 769 config LOWMEM_SIZE
 770         hex "Maximum low memory size (in bytes)" if LOWMEM_SIZE_BOOL
 771         default "0x30000000"
 772
 773 config LOWMEM_CAM_NUM_BOOL
 774         bool "Set number of CAMs to use to map low memory"
 775         depends on ADVANCED_OPTIONS && FSL_BOOKE
 776         help
 777           This option allows you to set the maximum number of CAM slots that
 778           will be used to map low memory.  There are a limited number of slots
 779           available and even more limited number that will fit in the L1 MMU.
 780           However, using more entries will allow mapping more low memory.  This
 781           can be useful in optimizing the layout of kernel virtual memory.
 782
 783           Say N here unless you know what you are doing.
 784
 785 config LOWMEM_CAM_NUM
 786         depends on FSL_BOOKE
 787         int "Number of CAMs to use to map low memory" if LOWMEM_CAM_NUM_BOOL
 788         default 3
 789
 790 config RELOCATABLE
 791         bool "Build a relocatable kernel (EXPERIMENTAL)"
 792         depends on EXPERIMENTAL && ADVANCED_OPTIONS && FLATMEM && FSL_BOOKE
 793         help
 794           This builds a kernel image that is capable of running at the
 795           location the kernel is loaded at (some alignment restrictions may
 796           exist).
 797
 798           One use is for the kexec on panic case where the recovery kernel
 799           must live at a different physical address than the primary
 800           kernel.
 801
 802           Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
 803           it has been loaded at and the compile time physical addresses
 804           CONFIG_PHYSICAL_START is ignored.  However CONFIG_PHYSICAL_START
 805           setting can still be useful to bootwrappers that need to know the
 806           load location of the kernel (eg. u-boot/mkimage).
 807
 808 config PAGE_OFFSET_BOOL
 809         bool "Set custom page offset address"
 810         depends on ADVANCED_OPTIONS
 811         help
 812           This option allows you to set the kernel virtual address at which
 813           the kernel will map low memory.  This can be useful in optimizing
 814           the virtual memory layout of the system.
 815
 816           Say N here unless you know what you are doing.
 817
 818 config PAGE_OFFSET
 819         hex "Virtual address of memory base" if PAGE_OFFSET_BOOL
 820         default "0xc0000000"
 821
 822 config KERNEL_START_BOOL
 823         bool "Set custom kernel base address"
 824         depends on ADVANCED_OPTIONS
 825         help
 826           This option allows you to set the kernel virtual address at which
 827           the kernel will be loaded.  Normally this should match PAGE_OFFSET
 828           however there are times (like kdump) that one might not want them
 829           to be the same.
 830
 831           Say N here unless you know what you are doing.
 832
 833 config KERNEL_START
 834         hex "Virtual address of kernel base" if KERNEL_START_BOOL
 835         default PAGE_OFFSET if PAGE_OFFSET_BOOL
 836         default "0xc2000000" if CRASH_DUMP
 837         default "0xc0000000"
 838
 839 config PHYSICAL_START_BOOL
 840         bool "Set physical address where the kernel is loaded"
 841         depends on ADVANCED_OPTIONS && FLATMEM && FSL_BOOKE
 842         help
 843           This gives the physical address where the kernel is loaded.
 844
 845           Say N here unless you know what you are doing.
 846
 847 config PHYSICAL_START
 848         hex "Physical address where the kernel is loaded" if PHYSICAL_START_BOOL
 849         default "0x02000000" if PPC_STD_MMU && CRASH_DUMP
 850         default "0x00000000"
 851
 852 config PHYSICAL_ALIGN
 853         hex
 854         default "0x04000000" if FSL_BOOKE
 855         help
 856           This value puts the alignment restrictions on physical address
 857           where kernel is loaded and run from. Kernel is compiled for an
 858           address which meets above alignment restriction.
 859
 860 config TASK_SIZE_BOOL
 861         bool "Set custom user task size"
 862         depends on ADVANCED_OPTIONS
 863         help
 864           This option allows you to set the amount of virtual address space
 865           allocated to user tasks.  This can be useful in optimizing the
 866           virtual memory layout of the system.
 867
 868           Say N here unless you know what you are doing.
 869
 870 config TASK_SIZE
 871         hex "Size of user task space" if TASK_SIZE_BOOL
 872         default "0x80000000" if PPC_PREP || PPC_8xx
 873         default "0xc0000000"
 874
 875 config CONSISTENT_SIZE_BOOL
 876         bool "Set custom consistent memory pool size"
 877         depends on ADVANCED_OPTIONS && NOT_COHERENT_CACHE
 878         help
 879           This option allows you to set the size of the
 880           consistent memory pool.  This pool of virtual memory
 881           is used to make consistent memory allocations.
 882
 883 config CONSISTENT_SIZE
 884         hex "Size of consistent memory pool" if CONSISTENT_SIZE_BOOL
 885         default "0x00200000" if NOT_COHERENT_CACHE
 886
 887 config PIN_TLB
 888         bool "Pinned Kernel TLBs (860 ONLY)"
 889         depends on ADVANCED_OPTIONS && 8xx
 890 endmenu
 891
 892 if PPC64
 893 config RELOCATABLE
 894         bool "Build a relocatable kernel"
 895         help
 896           This builds a kernel image that is capable of running anywhere
 897           in the RMA (real memory area) at any 16k-aligned base address.
 898           The kernel is linked as a position-independent executable (PIE)
 899           and contains dynamic relocations which are processed early
 900           in the bootup process.
 901
 902           One use is for the kexec on panic case where the recovery kernel
 903           must live at a different physical address than the primary
 904           kernel.
 905
 906 config PAGE_OFFSET
 907         hex
 908         default "0xc000000000000000"
 909 config KERNEL_START
 910         hex
 911         default "0xc000000000000000"
 912 config PHYSICAL_START
 913         hex
 914         default "0x00000000"
 915 endif
 916
 917 source "net/Kconfig"
 918
 919 source "drivers/Kconfig"
 920
 921 source "fs/Kconfig"
 922
 923 source "arch/powerpc/sysdev/qe_lib/Kconfig"
 924
 925 source "lib/Kconfig"
 926
 927 source "arch/powerpc/Kconfig.debug"
 928
 929 source "security/Kconfig"
 930
 931 config KEYS_COMPAT
 932         bool
 933         depends on COMPAT && KEYS
 934         default y
 935
 936 source "crypto/Kconfig"
 937
 938 config PPC_CLOCK
 939         bool
 940         default n
 941         select HAVE_CLK
 942
 943 config PPC_LIB_RHEAP
 944         bool
 945
 946 source "arch/powerpc/kvm/Kconfig"