# SPDX-License-Identifier: GPL-2.0
config XTENSA
def_bool y
select ARCH_32BIT_OFF_T
select ARCH_HAS_CPU_CACHE_ALIASING
select ARCH_HAS_BINFMT_FLAT if !MMU
select ARCH_HAS_CURRENT_STACK_POINTER
select ARCH_HAS_DEBUG_VM_PGTABLE
select ARCH_HAS_DMA_PREP_COHERENT if MMU
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_HAS_KCOV
select ARCH_HAS_SYNC_DMA_FOR_CPU if MMU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE if MMU
select ARCH_HAS_DMA_SET_UNCACHED if MMU
select ARCH_HAS_STRNCPY_FROM_USER if !KASAN
select ARCH_HAS_STRNLEN_USER
select ARCH_NEED_CMPXCHG_1_EMU
select ARCH_USE_MEMTEST
select ARCH_USE_QUEUED_RWLOCKS
select ARCH_USE_QUEUED_SPINLOCKS
select ARCH_WANT_IPC_PARSE_VERSION
select BUILDTIME_TABLE_SORT
select GENERIC_BUILTIN_DTB
select CLONE_BACKWARDS
select COMMON_CLK
select DMA_NONCOHERENT_MMAP if MMU
select GENERIC_ATOMIC64
select GENERIC_IRQ_SHOW
select GENERIC_LIB_CMPDI2
select GENERIC_LIB_MULDI3
select GENERIC_LIB_UCMPDI2
select GENERIC_PCI_IOMAP
select GENERIC_SCHED_CLOCK
select GENERIC_IOREMAP if MMU
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
select HAVE_ARCH_KCSAN
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_ASM_MODVERSIONS
select HAVE_CONTEXT_TRACKING_USER
select HAVE_DEBUG_KMEMLEAK
select HAVE_DMA_CONTIGUOUS
select HAVE_EXIT_THREAD
select HAVE_FUNCTION_TRACER
select HAVE_GCC_PLUGINS if GCC_VERSION >= 120000
select HAVE_HW_BREAKPOINT if PERF_EVENTS
select HAVE_IRQ_TIME_ACCOUNTING
select HAVE_PAGE_SIZE_4KB
select HAVE_PCI
select HAVE_PERF_EVENTS
select HAVE_STACKPROTECTOR
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_VIRT_CPU_ACCOUNTING_GEN
select IRQ_DOMAIN
select LOCK_MM_AND_FIND_VMA
select MODULES_USE_ELF_RELA
select PERF_USE_VMALLOC
select TRACE_IRQFLAGS_SUPPORT
help
Xtensa processors are 32-bit RISC machines designed by Tensilica
primarily for embedded systems. These processors are both
configurable and extensible. The Linux port to the Xtensa
architecture supports all processor configurations and extensions,
with reasonable minimum requirements. The Xtensa Linux project has
a home page at <
http://www.linux-xtensa.org/>.
config GENERIC_HWEIGHT
def_bool y
config ARCH_HAS_ILOG2_U32
def_bool n
config ARCH_HAS_ILOG2_U64
def_bool n
config ARCH_MTD_XIP
def_bool y
config NO_IOPORT_MAP
def_bool n
config HZ
int
default 100
config LOCKDEP_SUPPORT
def_bool y
config STACKTRACE_SUPPORT
def_bool y
config MMU
def_bool n
select PFAULT
config HAVE_XTENSA_GPIO32
def_bool n
config KASAN_SHADOW_OFFSET
hex
default 0x6e400000
config CPU_BIG_ENDIAN
def_bool $(success,test "$(shell,echo __XTENSA_EB__ | $(CC) -E -P -)" = 1)
config CPU_LITTLE_ENDIAN
def_bool !CPU_BIG_ENDIAN
config CC_HAVE_CALL0_ABI
def_bool $(success,test "$(shell,echo __XTENSA_CALL0_ABI__ | $(CC) -mabi=call0 -E -P - 2>/d
ev/null)" = 1)
menu "Processor type and features"
choice
prompt "Xtensa Processor Configuration"
default XTENSA_VARIANT_FSF
config XTENSA_VARIANT_FSF
bool "fsf - default (not generic) configuration"
select MMU
config XTENSA_VARIANT_DC232B
bool "dc232b - Diamond 232L Standard Core Rev.B (LE)"
select MMU
select HAVE_XTENSA_GPIO32
help
This variant refers to Tensilica's Diamond 232L Standard core Rev.B (LE).
config XTENSA_VARIANT_DC233C
bool "dc233c - Diamond 233L Standard Core Rev.C (LE)"
select MMU
select HAVE_XTENSA_GPIO32
help
This variant refers to Tensilica's Diamond 233L Standard core Rev.C (LE).
config XTENSA_VARIANT_CUSTOM
bool "Custom Xtensa processor configuration"
select HAVE_XTENSA_GPIO32
help
Select this variant to use a custom Xtensa processor configuration.
You will be prompted for a processor variant CORENAME.
endchoice
config XTENSA_VARIANT_CUSTOM_NAME
string "Xtensa Processor Custom Core Variant Name"
depends on XTENSA_VARIANT_CUSTOM
help
Provide the name of a custom Xtensa processor variant.
This CORENAME selects arch/xtensa/variants/CORENAME.
Don't forget you have to select MMU if you have one.
config XTENSA_VARIANT_NAME
string
default "dc232b" if XTENSA_VARIANT_DC232B
default "dc233c" if XTENSA_VARIANT_DC233C
default "fsf" if XTENSA_VARIANT_FSF
default XTENSA_VARIANT_CUSTOM_NAME if XTENSA_VARIANT_CUSTOM
config XTENSA_VARIANT_MMU
bool "Core variant has a Full MMU (TLB, Pages, Protection, etc)"
depends on XTENSA_VARIANT_CUSTOM
default y
select MMU
help
Build a Conventional Kernel with full MMU support,
ie: it supports a TLB with auto-loading, page protection.
config XTENSA_VARIANT_HAVE_PERF_EVENTS
bool "Core variant has Performance Monitor Module"
depends on XTENSA_VARIANT_CUSTOM
default n
help
Enable if core variant has Performance Monitor Module with
External Registers Interface.
If unsure, say N.
config XTENSA_FAKE_NMI
bool "Treat PMM IRQ as NMI"
depends on XTENSA_VARIANT_HAVE_PERF_EVENTS
default n
help
If PMM IRQ is the only IRQ at EXCM level it is safe to
treat it as NMI, which improves accuracy of profiling.
If there are other interrupts at or above PMM IRQ priority level
but not above the EXCM level, PMM IRQ still may be treated as NMI,
but only if these IRQs are not used. There will be a build warning
saying that this is not safe, and a bugcheck if one of these IRQs
actually fire.
If unsure, say N.
config PFAULT
bool "Handle protection faults" if EXPERT && !MMU
default y
help
Handle protection faults. MMU configurations must enable it.
noMMU configurations may disable it if used memory map never
generates protection faults or faults are always fatal.
If unsure, say Y.
config XTENSA_UNALIGNED_USER
bool "Unaligned memory access in user space"
help
The Xtensa architecture currently does not handle unaligned
memory accesses in hardware but through an exception handler.
Per default, unaligned memory accesses are disabled in user space.
Say Y here to enable unaligned memory access in user space.
config XTENSA_LOAD_STORE
bool "Load/store exception handler for memory only readable with l32"
help
The Xtensa architecture only allows reading memory attached to its
instruction bus with l32r and l32i instructions, all other
instructions raise an exception with the LoadStoreErrorCause code.
This makes it hard to use some configurations, e.g. store string
literals in FLASH memory attached to the instruction bus.
Say Y here to enable exception handler that allows transparent
byte and 2-byte access to memory attached to instruction bus.
config HAVE_SMP
bool "System Supports SMP (MX)"
depends on XTENSA_VARIANT_CUSTOM
select XTENSA_MX
help
This option is used to indicate that the system-on-a-chip (SOC)
supports Multiprocessing. Multiprocessor support implemented above
the CPU core definition and currently needs to be selected manually.
Multiprocessor support is implemented with external cache and
interrupt controllers.
The MX interrupt distributer adds Interprocessor Interrupts
and causes the IRQ numbers to be increased by 4 for devices
like the open cores ethernet driver and the serial interface.
You still have to select "Enable SMP" to enable SMP on this SOC.
config SMP
bool "Enable Symmetric multi-processing support"
depends on HAVE_SMP
select GENERIC_SMP_IDLE_THREAD
help
Enabled SMP Software; allows more than one CPU/CORE
to be activated during startup.
config NR_CPUS
depends on SMP
int "Maximum number of CPUs (2-32)"
range 2 32
default "4"
config HOTPLUG_CPU
bool "Enable CPU hotplug support"
depends on SMP
help
Say Y here to allow turning CPUs off and on. CPUs can be
controlled through /sys/devices/system/cpu.
Say N if you want to disable CPU hotplug.
config SECONDARY_RESET_VECTOR
bool "Secondary cores use alternative reset vector"
default y
depends on HAVE_SMP
help
Secondary cores may be configured to use alternative reset vector,
or all cores may use primary reset vector.
Say Y here to supply handler for the alternative reset location.
config FAST_SYSCALL_XTENSA
bool "Enable fast atomic syscalls"
default n
help
fast_syscall_xtensa is a syscall that can make atomic operations
on UP kernel when processor has no s32c1i support.
This syscall is deprecated. It may have issues when called with
invalid arguments. It is provided only for backwards compatibility.
Only enable it if your userspace software requires it.
If unsure, say N.
config FAST_SYSCALL_SPILL_REGISTERS
bool "Enable spill registers syscall"
default n
help
fast_syscall_spill_registers is a syscall that spills all active
register windows of a calling userspace task onto its stack.
This syscall is deprecated. It may have issues when called with
invalid arguments. It is provided only for backwards compatibility.
Only enable it if your userspace software requires it.
If unsure, say N.
choice
prompt "Kernel ABI"
default KERNEL_ABI_DEFAULT
help
Select ABI for the kernel code. This ABI is independent of the
supported userspace ABI and any combination of the
kernel/userspace ABI is possible and should work.
In case both kernel and userspace support only call0 ABI
all register windows support code will be omitted from the
build.
If unsure, choose the default ABI.
config KERNEL_ABI_DEFAULT
bool "Default ABI"
help
Select this option to compile kernel code with the default ABI
selected for the toolchain.
Normally cores with windowed registers option use windowed ABI and
cores without it use call0 ABI.
config KERNEL_ABI_CALL0
bool "Call0 ABI" if CC_HAVE_CALL0_ABI
help
Select this option to compile kernel code with call0 ABI even with
toolchain that defaults to windowed ABI.
When this option is not selected the default toolchain ABI will
be used for the kernel code.
endchoice
config USER_ABI_CALL0
bool
choice
prompt "Userspace ABI"
default USER_ABI_DEFAULT
help
Select supported userspace ABI.
If unsure, choose the default ABI.
config USER_ABI_DEFAULT
bool "Default ABI only"
help
Assume default userspace ABI. For XEA2 cores it is windowed ABI.
call0 ABI binaries may be run on such kernel, but signal delivery
will not work correctly for them.
config USER_ABI_CALL0_ONLY
bool "Call0 ABI only"
select USER_ABI_CALL0
help
Select this option to support only call0 ABI in userspace.
Windowed ABI binaries will crash with a segfault caused by
an illegal instruction exception on the first 'entry' opcode.
Choose this option if you're planning to run only user code
built with call0 ABI.
config USER_ABI_CALL0_PROBE
bool "Support both windowed and call0 ABI by probing"
select USER_ABI_CALL0
help
Select this option to support both windowed and call0 userspace
ABIs. When enabled all processes are started with PS.WOE disabled
and a fast user exception handler for an illegal instruction is
used to turn on PS.WOE bit on the first 'entry' opcode executed by
the userspace.
This option should be enabled for the kernel that must support
both call0 and windowed ABIs in userspace at the same time.
Note that Xtensa ISA does not guarantee that entry opcode will
raise an illegal instruction exception on cores with XEA2 when
PS.WOE is disabled, check whether the target core supports it.
endchoice
endmenu
config XTENSA_CALIBRATE_CCOUNT
def_bool n
help
On some platforms (XT2000, for example), the CPU clock rate can
vary. The frequency can be determined, however, by measuring
against a well known, fixed frequency, such as an UART oscillator.
config SERIAL_CONSOLE
def_bool n
config PLATFORM_HAVE_XIP
def_bool n
menu "Platform options"
choice
prompt "Xtensa System Type"
default XTENSA_PLATFORM_ISS
config XTENSA_PLATFORM_ISS
bool "ISS"
select XTENSA_CALIBRATE_CCOUNT
select SERIAL_CONSOLE
help
ISS is an acronym for Tensilica's Instruction Set Simulator.
config XTENSA_PLATFORM_XT2000
bool "XT2000"
help
XT2000 is the name of Tensilica's feature-rich emulation platform.
This hardware is capable of running a full Linux distribution.
config XTENSA_PLATFORM_XTFPGA
bool "XTFPGA"
select ETHOC if ETHERNET
select PLATFORM_WANT_DEFAULT_MEM if !MMU
select SERIAL_CONSOLE
select XTENSA_CALIBRATE_CCOUNT
select PLATFORM_HAVE_XIP
help
XTFPGA is the name of Tensilica board family (LX60, LX110, LX200, ML605).
This hardware is capable of running a full Linux distribution.
endchoice
config PLATFORM_NR_IRQS
int
default 3 if XTENSA_PLATFORM_XT2000
default 0
config XTENSA_CPU_CLOCK
int "CPU clock rate [MHz]"
depends on !XTENSA_CALIBRATE_CCOUNT
default 16
config GENERIC_CALIBRATE_DELAY
bool "Auto calibration of the BogoMIPS value"
help
The BogoMIPS value can easily be derived from the CPU frequency.
config CMDLINE_BOOL
bool "Default bootloader kernel arguments"
config CMDLINE
string "Initial kernel command string"
depends on CMDLINE_BOOL
default "console=ttyS0,38400 root=/dev/ram"
help
On some architectures (EBSA110 and CATS), there is currently no way
for the boot loader to pass arguments to the kernel. For these
architectures, you should supply some command-line options at build
time by entering them here. As a minimum, you should specify the
memory size and the root device (e.g., mem=64M root=/dev/nfs).
config USE_OF
bool "Flattened Device Tree support"
select OF
select OF_EARLY_FLATTREE
help
Include support for flattened device tree machine descriptions.
config BUILTIN_DTB_NAME
string "DTB to build into the kernel image"
depends on OF
config PARSE_BOOTPARAM
bool "Parse bootparam block"
default y
help
Parse parameters passed to the kernel from the bootloader. It may
be disabled if the kernel is known to run without the bootloader.
If unsure, say Y.
choice
prompt "Semihosting interface"
default XTENSA_SIMCALL_ISS
depends on XTENSA_PLATFORM_ISS
help
Choose semihosting interface that will be used for serial port,
block device and networking.
config XTENSA_SIMCALL_ISS
bool "simcall"
help
Use simcall instruction. simcall is only available on simulators,
it does nothing on hardware.
config XTENSA_SIMCALL_GDBIO
bool "GDBIO"
help
Use break instruction. It is available on real hardware when GDB
is attached to it via JTAG.
endchoice
config BLK_DEV_SIMDISK
tristate "Host file-based simulated block device support"
default n
depends on XTENSA_PLATFORM_ISS && BLOCK
help
Create block devices that map to files in the host file system.
Device binding to host file may be changed at runtime via proc
interface provided the device is not in use.
config BLK_DEV_SIMDISK_COUNT
int "Number of host file-based simulated block devices"
range 1 10
depends on BLK_DEV_SIMDISK
default 2
help
This is the default minimal number of created block devices.
Kernel/module parameter 'simdisk_count' may be used to change this
value at runtime. More file names (but no more than 10) may be
specified as parameters, simdisk_count grows accordingly.
config SIMDISK0_FILENAME
string "Host filename for the first simulated device"
depends on BLK_DEV_SIMDISK = y
default ""
help
Attach a first simdisk to a host file. Conventionally, this file
contains a root file system.
config SIMDISK1_FILENAME
string "Host filename for the second simulated device"
depends on BLK_DEV_SIMDISK = y && BLK_DEV_SIMDISK_COUNT != 1
default ""
help
Another simulated disk in a host file for a buildroot-independent
storage.
config XTFPGA_LCD
bool "Enable XTFPGA LCD driver"
depends on XTENSA_PLATFORM_XTFPGA
default n
help
There's a 2x16 LCD on most of XTFPGA boards, kernel may output
progress messages there during bootup/shutdown. It may be useful
during board bringup.
If unsure, say N.
config XTFPGA_LCD_BASE_ADDR
hex "XTFPGA LCD base address"
depends on XTFPGA_LCD
default "0x0d0c0000"
help
Base address of the LCD controller inside KIO region.
Different boards from XTFPGA family have LCD controller at different
addresses. Please consult prototyping user guide for your board for
the correct address. Wrong address here may lead to hardware lockup.
config XTFPGA_LCD_8BIT_ACCESS
bool "Use 8-bit access to XTFPGA LCD"
depends on XTFPGA_LCD
default n
help
LCD may be connected with 4- or 8-bit interface, 8-bit access may
only be used with 8-bit interface. Please consult prototyping user
guide for your board for the correct interface width.
comment "Kernel memory layout"
config INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
bool "Initialize Xtensa MMU inside the Linux kernel code"
depends on !XTENSA_VARIANT_FSF && !XTENSA_VARIANT_DC232B
default y if XTENSA_VARIANT_DC233C || XTENSA_VARIANT_CUSTOM
help
Earlier version initialized the MMU in the exception vector
before jumping to _startup in head.S and had an advantage that
it was possible to place a software breakpoint at 'reset' and
then enter your normal kernel breakpoints once the MMU was mapped
to the kernel mappings (0XC0000000).
This unfortunately won't work for U-Boot and likely also won't
work for using KEXEC to have a hot kernel ready for doing a
KDUMP.
So now the MMU is initialized in head.S but it's necessary to
use hardware breakpoints (gdb 'hbreak' cmd) to break at _startup.
xt-gdb can't place a Software Breakpoint in the 0XD region prior
to mapping the MMU and after mapping even if the area of low memory
was mapped gdb wouldn't remove the breakpoint on hitting it as the
PC wouldn't match. Since Hardware Breakpoints are recommended for
Linux configurations it seems reasonable to just assume they exist
and leave this older mechanism for unfortunate souls that choose
not to follow Tensilica's recommendation.
Selecting this will cause U-Boot to set the KERNEL Load and Entry
address at 0x00003000 instead of the mapped std of 0xD0003000.
If in doubt, say Y.
config XIP_KERNEL
bool "Kernel Execute-In-Place from ROM"
depends on PLATFORM_HAVE_XIP
help
Execute-In-Place allows the kernel to run from non-volatile storage
directly addressable by the CPU, such as NOR flash. This saves RAM
space since the text section of the kernel is not loaded from flash
to RAM. Read-write sections, such as the data section and stack,
are still copied to RAM. The XIP kernel is not compressed since
it has to run directly from flash, so it will take more space to
store it. The flash address used to link the kernel object files,
and for storing it, is configuration dependent. Therefore, if you
say Y here, you must know the proper physical address where to
store the kernel image depending on your own flash memory usage.
Also note that the make target becomes "make xipImage" rather than
"make Image" or "make uImage". The final kernel binary to put in
ROM memory will be arch/xtensa/boot/xipImage.
If unsure, say N.
config MEMMAP_CACHEATTR
hex "Cache attributes for the memory address space"
depends on !MMU
default 0x22222222
help
These cache attributes are set up for noMMU systems. Each hex digit
specifies cache attributes for the corresponding 512MB memory
region: bits 0..3 -- for addresses 0x00000000..0x1fffffff,
bits 4..7 -- for addresses 0x20000000..0x3fffffff, and so on.
Cache attribute values are specific for the MMU type.
For region protection MMUs:
1: WT cached,
2: cache bypass,
4: WB cached,
f: illegal.
For full MMU:
bit 0: executable,
bit 1: writable,
bits 2..3:
0: cache bypass,
1: WB cache,
2: WT cache,
3: special (c and e are illegal, f is reserved).
For MPU:
0: illegal,
1: WB cache,
2: WB, no-write-allocate cache,
3: WT cache,
4: cache bypass.
config KSEG_PADDR
hex "Physical address of the KSEG mapping"
depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX && MMU
default 0x00000000
help
This is the physical address where KSEG is mapped. Please refer to
the chosen KSEG layout help for the required address alignment.
Unpacked kernel image (including vectors) must be located completely
within KSEG.
Physical memory below this address is not available to linux.
If unsure, leave the default value here.
config KERNEL_VIRTUAL_ADDRESS
hex "Kernel virtual address"
depends on MMU && XIP_KERNEL
default 0xd0003000
help
This is the virtual address where the XIP kernel is mapped.
XIP kernel may be mapped into KSEG or KIO region, virtual address
provided here must match kernel load address provided in
KERNEL_LOAD_ADDRESS.
config KERNEL_LOAD_ADDRESS
hex "Kernel load address"
default 0x60003000 if !MMU
default 0x00003000 if MMU && INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
default 0xd0003000 if MMU && !INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
help
This is the address where the kernel is loaded.
It is virtual address for MMUv2 configurations and physical address
for all other configurations.
If unsure, leave the default value here.
choice
prompt "Relocatable vectors location"
default XTENSA_VECTORS_IN_TEXT
help
Choose whether relocatable vectors are merged into the kernel .text
or placed separately at runtime. This option does not affect
configurations without VECBASE register where vectors are always
placed at their hardware-defined locations.
config XTENSA_VECTORS_IN_TEXT
bool "Merge relocatable vectors into kernel text"
depends on !MTD_XIP
help
This option puts relocatable vectors into the kernel .text section
with proper alignment.
This is a safe choice for most configurations.
config XTENSA_VECTORS_SEPARATE
bool "Put relocatable vectors at fixed address"
help
This option puts relocatable vectors at specific virtual address.
Vectors are merged with the .init data in the kernel image and
are copied into their designated location during kernel startup.
Use it to put vectors into IRAM or out of FLASH on kernels with
XIP-aware MTD support.
endchoice
config VECTORS_ADDR
hex "Kernel vectors virtual address"
default 0x00000000
depends on XTENSA_VECTORS_SEPARATE
help
This is the virtual address of the (relocatable) vectors base.
It must be within KSEG if MMU is used.
config XIP_DATA_ADDR
hex "XIP kernel data virtual address"
depends on XIP_KERNEL
default 0x00000000
help
This is the virtual address where XIP kernel data is copied.
It must be within KSEG if MMU is used.
config PLATFORM_WANT_DEFAULT_MEM
def_bool n
config DEFAULT_MEM_START
hex
prompt "PAGE_OFFSET/PHYS_OFFSET" if !MMU && PLATFORM_WANT_DEFAULT_MEM
default 0x60000000 if PLATFORM_WANT_DEFAULT_MEM
default 0x00000000
help
This is the base address used for both PAGE_OFFSET and PHYS_OFFSET
in noMMU configurations.
If unsure, leave the default value here.
choice
prompt "KSEG layout"
depends on MMU
default XTENSA_KSEG_MMU_V2
config XTENSA_KSEG_MMU_V2
bool "MMUv2: 128MB cached + 128MB uncached"
help
MMUv2 compatible kernel memory map: TLB way 5 maps 128MB starting
at KSEG_PADDR to 0xd0000000 with cache and to 0xd8000000
without cache.
KSEG_PADDR must be aligned to 128MB.
config XTENSA_KSEG_256M
bool "256MB cached + 256MB uncached"
depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
help
TLB way 6 maps 256MB starting at KSEG_PADDR to 0xb0000000
with cache and to 0xc0000000 without cache.
KSEG_PADDR must be aligned to 256MB.
config XTENSA_KSEG_512M
bool "512MB cached + 512MB uncached"
depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
help
TLB way 6 maps 512MB starting at KSEG_PADDR to 0xa0000000
with cache and to 0xc0000000 without cache.
KSEG_PADDR must be aligned to 256MB.
endchoice
config HIGHMEM
bool "High Memory Support"
depends on MMU
select KMAP_LOCAL
help
Linux can use the full amount of RAM in the system by
default. However, the default MMUv2 setup only maps the
lowermost 128 MB of memory linearly to the areas starting
at 0xd0000000 (cached) and 0xd8000000 (uncached).
When there are more than 128 MB memory in the system not
all of it can be "permanently mapped" by the kernel.
The physical memory that's not permanently mapped is called
"high memory".
If you are compiling a kernel which will never run on a
machine with more than 128 MB total physical RAM, answer
N here.
If unsure, say Y.
config ARCH_FORCE_MAX_ORDER
int "Order of maximal physically contiguous allocations"
default "10"
help
The kernel page allocator limits the size of maximal physically
contiguous allocations. The limit is called MAX_PAGE_ORDER and it
defines the maximal power of two of number of pages that can be
allocated as a single contiguous block. This option allows
overriding the default setting when ability to allocate very
large blocks of physically contiguous memory is required.
Don't change if unsure.
endmenu
menu "Power management options"
config ARCH_HIBERNATION_POSSIBLE
def_bool y
source "kernel/power/Kconfig"
endmenu
