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linux/arch/arc/Kconfig
Zhaoxiu Zeng fff7fb0b2d lib/GCD.c: use binary GCD algorithm instead of Euclidean 
The binary GCD algorithm is based on the following facts:
	1. If a and b are all evens, then gcd(a,b) = 2 * gcd(a/2, b/2)
	2. If a is even and b is odd, then gcd(a,b) = gcd(a/2, b)
	3. If a and b are all odds, then gcd(a,b) = gcd((a-b)/2, b) = gcd((a+b)/2, b)

Even on x86 machines with reasonable division hardware, the binary
algorithm runs about 25% faster (80% the execution time) than the
division-based Euclidian algorithm.

On platforms like Alpha and ARMv6 where division is a function call to
emulation code, it's even more significant.

There are two variants of the code here, depending on whether a fast
__ffs (find least significant set bit) instruction is available.  This
allows the unpredictable branches in the bit-at-a-time shifting loop to
be eliminated.

If fast __ffs is not available, the "even/odd" GCD variant is used.

I use the following code to benchmark:

	#include <stdio.h>
	#include <stdlib.h>
	#include <stdint.h>
	#include <string.h>
	#include <time.h>
	#include <unistd.h>

	#define swap(a, b) \
		do { \
			a ^= b; \
			b ^= a; \
			a ^= b; \
		} while (0)

	unsigned long gcd0(unsigned long a, unsigned long b)
	{
		unsigned long r;

		if (a < b) {
			swap(a, b);
		}

		if (b == 0)
			return a;

		while ((r = a % b) != 0) {
			a = b;
			b = r;
		}

		return b;
	}

	unsigned long gcd1(unsigned long a, unsigned long b)
	{
		unsigned long r = a | b;

		if (!a || !b)
			return r;

		b >>= __builtin_ctzl(b);

		for (;;) {
			a >>= __builtin_ctzl(a);
			if (a == b)
				return a << __builtin_ctzl(r);

			if (a < b)
				swap(a, b);
			a -= b;
		}
	}

	unsigned long gcd2(unsigned long a, unsigned long b)
	{
		unsigned long r = a | b;

		if (!a || !b)
			return r;

		r &= -r;

		while (!(b & r))
			b >>= 1;

		for (;;) {
			while (!(a & r))
				a >>= 1;
			if (a == b)
				return a;

			if (a < b)
				swap(a, b);
			a -= b;
			a >>= 1;
			if (a & r)
				a += b;
			a >>= 1;
		}
	}

	unsigned long gcd3(unsigned long a, unsigned long b)
	{
		unsigned long r = a | b;

		if (!a || !b)
			return r;

		b >>= __builtin_ctzl(b);
		if (b == 1)
			return r & -r;

		for (;;) {
			a >>= __builtin_ctzl(a);
			if (a == 1)
				return r & -r;
			if (a == b)
				return a << __builtin_ctzl(r);

			if (a < b)
				swap(a, b);
			a -= b;
		}
	}

	unsigned long gcd4(unsigned long a, unsigned long b)
	{
		unsigned long r = a | b;

		if (!a || !b)
			return r;

		r &= -r;

		while (!(b & r))
			b >>= 1;
		if (b == r)
			return r;

		for (;;) {
			while (!(a & r))
				a >>= 1;
			if (a == r)
				return r;
			if (a == b)
				return a;

			if (a < b)
				swap(a, b);
			a -= b;
			a >>= 1;
			if (a & r)
				a += b;
			a >>= 1;
		}
	}

	static unsigned long (*gcd_func[])(unsigned long a, unsigned long b) = {
		gcd0, gcd1, gcd2, gcd3, gcd4,
	};

	#define TEST_ENTRIES (sizeof(gcd_func) / sizeof(gcd_func[0]))

	#if defined(__x86_64__)

	#define rdtscll(val) do { \
		unsigned long __a,__d; \
		__asm__ __volatile__("rdtsc" : "=a" (__a), "=d" (__d)); \
		(val) = ((unsigned long long)__a) | (((unsigned long long)__d)<<32); \
	} while(0)

	static unsigned long long benchmark_gcd_func(unsigned long (*gcd)(unsigned long, unsigned long),
								unsigned long a, unsigned long b, unsigned long *res)
	{
		unsigned long long start, end;
		unsigned long long ret;
		unsigned long gcd_res;

		rdtscll(start);
		gcd_res = gcd(a, b);
		rdtscll(end);

		if (end >= start)
			ret = end - start;
		else
			ret = ~0ULL - start + 1 + end;

		*res = gcd_res;
		return ret;
	}

	#else

	static inline struct timespec read_time(void)
	{
		struct timespec time;
		clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &time);
		return time;
	}

	static inline unsigned long long diff_time(struct timespec start, struct timespec end)
	{
		struct timespec temp;

		if ((end.tv_nsec - start.tv_nsec) < 0) {
			temp.tv_sec = end.tv_sec - start.tv_sec - 1;
			temp.tv_nsec = 1000000000ULL + end.tv_nsec - start.tv_nsec;
		} else {
			temp.tv_sec = end.tv_sec - start.tv_sec;
			temp.tv_nsec = end.tv_nsec - start.tv_nsec;
		}

		return temp.tv_sec * 1000000000ULL + temp.tv_nsec;
	}

	static unsigned long long benchmark_gcd_func(unsigned long (*gcd)(unsigned long, unsigned long),
								unsigned long a, unsigned long b, unsigned long *res)
	{
		struct timespec start, end;
		unsigned long gcd_res;

		start = read_time();
		gcd_res = gcd(a, b);
		end = read_time();

		*res = gcd_res;
		return diff_time(start, end);
	}

	#endif

	static inline unsigned long get_rand()
	{
		if (sizeof(long) == 8)
			return (unsigned long)rand() << 32 | rand();
		else
			return rand();
	}

	int main(int argc, char **argv)
	{
		unsigned int seed = time(0);
		int loops = 100;
		int repeats = 1000;
		unsigned long (*res)[TEST_ENTRIES];
		unsigned long long elapsed[TEST_ENTRIES];
		int i, j, k;

		for (;;) {
			int opt = getopt(argc, argv, "n:r:s:");
			/* End condition always first */
			if (opt == -1)
				break;

			switch (opt) {
			case 'n':
				loops = atoi(optarg);
				break;
			case 'r':
				repeats = atoi(optarg);
				break;
			case 's':
				seed = strtoul(optarg, NULL, 10);
				break;
			default:
				/* You won't actually get here. */
				break;
			}
		}

		res = malloc(sizeof(unsigned long) * TEST_ENTRIES * loops);
		memset(elapsed, 0, sizeof(elapsed));

		srand(seed);
		for (j = 0; j < loops; j++) {
			unsigned long a = get_rand();
			/* Do we have args? */
			unsigned long b = argc > optind ? strtoul(argv[optind], NULL, 10) : get_rand();
			unsigned long long min_elapsed[TEST_ENTRIES];
			for (k = 0; k < repeats; k++) {
				for (i = 0; i < TEST_ENTRIES; i++) {
					unsigned long long tmp = benchmark_gcd_func(gcd_func[i], a, b, &res[j][i]);
					if (k == 0 || min_elapsed[i] > tmp)
						min_elapsed[i] = tmp;
				}
			}
			for (i = 0; i < TEST_ENTRIES; i++)
				elapsed[i] += min_elapsed[i];
		}

		for (i = 0; i < TEST_ENTRIES; i++)
			printf("gcd%d: elapsed %llu\n", i, elapsed[i]);

		k = 0;
		srand(seed);
		for (j = 0; j < loops; j++) {
			unsigned long a = get_rand();
			unsigned long b = argc > optind ? strtoul(argv[optind], NULL, 10) : get_rand();
			for (i = 1; i < TEST_ENTRIES; i++) {
				if (res[j][i] != res[j][0])
					break;
			}
			if (i < TEST_ENTRIES) {
				if (k == 0) {
					k = 1;
					fprintf(stderr, "Error:\n");
				}
				fprintf(stderr, "gcd(%lu, %lu): ", a, b);
				for (i = 0; i < TEST_ENTRIES; i++)
					fprintf(stderr, "%ld%s", res[j][i], i < TEST_ENTRIES - 1 ? ", " : "\n");
			}
		}

		if (k == 0)
			fprintf(stderr, "PASS\n");

		free(res);

		return 0;
	}

Compiled with "-O2", on "VirtualBox 4.4.0-22-generic #38-Ubuntu x86_64" got:

  zhaoxiuzeng@zhaoxiuzeng-VirtualBox:~/develop$ ./gcd -r 500000 -n 10
  gcd0: elapsed 10174
  gcd1: elapsed 2120
  gcd2: elapsed 2902
  gcd3: elapsed 2039
  gcd4: elapsed 2812
  PASS
  zhaoxiuzeng@zhaoxiuzeng-VirtualBox:~/develop$ ./gcd -r 500000 -n 10
  gcd0: elapsed 9309
  gcd1: elapsed 2280
  gcd2: elapsed 2822
  gcd3: elapsed 2217
  gcd4: elapsed 2710
  PASS
  zhaoxiuzeng@zhaoxiuzeng-VirtualBox:~/develop$ ./gcd -r 500000 -n 10
  gcd0: elapsed 9589
  gcd1: elapsed 2098
  gcd2: elapsed 2815
  gcd3: elapsed 2030
  gcd4: elapsed 2718
  PASS
  zhaoxiuzeng@zhaoxiuzeng-VirtualBox:~/develop$ ./gcd -r 500000 -n 10
  gcd0: elapsed 9914
  gcd1: elapsed 2309
  gcd2: elapsed 2779
  gcd3: elapsed 2228
  gcd4: elapsed 2709
  PASS

[akpm@linux-foundation.org: avoid #defining a CONFIG_ variable]
Signed-off-by: Zhaoxiu Zeng <zhaoxiu.zeng@gmail.com>
Signed-off-by: George Spelvin <linux@horizon.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20 17:58:30 -07:00

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#
# Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
#
config ARC
def_bool y
select ARCH_SUPPORTS_ATOMIC_RMW if ARC_HAS_LLSC
select BUILDTIME_EXTABLE_SORT
select CLKSRC_OF
select CLONE_BACKWARDS
select COMMON_CLK
select GENERIC_ATOMIC64
select GENERIC_CLOCKEVENTS
select GENERIC_FIND_FIRST_BIT
# for now, we don't need GENERIC_IRQ_PROBE, CONFIG_GENERIC_IRQ_CHIP
select GENERIC_IRQ_SHOW
select GENERIC_PCI_IOMAP
select GENERIC_PENDING_IRQ if SMP
select GENERIC_SMP_IDLE_THREAD
select HAVE_ARCH_KGDB
select HAVE_ARCH_TRACEHOOK
select HAVE_FUTEX_CMPXCHG
select HAVE_IOREMAP_PROT
select HAVE_KPROBES
select HAVE_KRETPROBES
select HAVE_MEMBLOCK
select HAVE_MOD_ARCH_SPECIFIC if ARC_DW2_UNWIND
select HAVE_OPROFILE
select HAVE_PERF_EVENTS
select HANDLE_DOMAIN_IRQ
select IRQ_DOMAIN
select MODULES_USE_ELF_RELA
select NO_BOOTMEM
select OF
select OF_EARLY_FLATTREE
select OF_RESERVED_MEM
select PERF_USE_VMALLOC
select HAVE_DEBUG_STACKOVERFLOW
select HAVE_GENERIC_DMA_COHERENT
config MIGHT_HAVE_PCI
bool
config TRACE_IRQFLAGS_SUPPORT
def_bool y
config LOCKDEP_SUPPORT
def_bool y
config SCHED_OMIT_FRAME_POINTER
def_bool y
config GENERIC_CSUM
def_bool y
config RWSEM_GENERIC_SPINLOCK
def_bool y
config ARCH_DISCONTIGMEM_ENABLE
def_bool y
config ARCH_FLATMEM_ENABLE
def_bool y
config MMU
def_bool y
config NO_IOPORT_MAP
def_bool y
config GENERIC_CALIBRATE_DELAY
def_bool y
config GENERIC_HWEIGHT
def_bool y
config STACKTRACE_SUPPORT
def_bool y
select STACKTRACE
config HAVE_ARCH_TRANSPARENT_HUGEPAGE
def_bool y
depends on ARC_MMU_V4
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "ARC Architecture Configuration"
menu "ARC Platform/SoC/Board"
source "arch/arc/plat-sim/Kconfig"
source "arch/arc/plat-tb10x/Kconfig"
source "arch/arc/plat-axs10x/Kconfig"
#New platform adds here
source "arch/arc/plat-eznps/Kconfig"
endmenu
choice
prompt "ARC Instruction Set"
default ISA_ARCOMPACT
config ISA_ARCOMPACT
bool "ARCompact ISA"
select CPU_NO_EFFICIENT_FFS
help
The original ARC ISA of ARC600/700 cores
config ISA_ARCV2
bool "ARC ISA v2"
help
ISA for the Next Generation ARC-HS cores
endchoice
menu "ARC CPU Configuration"
choice
prompt "ARC Core"
default ARC_CPU_770 if ISA_ARCOMPACT
default ARC_CPU_HS if ISA_ARCV2
if ISA_ARCOMPACT
config ARC_CPU_750D
bool "ARC750D"
select ARC_CANT_LLSC
help
Support for ARC750 core
config ARC_CPU_770
bool "ARC770"
select ARC_HAS_SWAPE
help
Support for ARC770 core introduced with Rel 4.10 (Summer 2011)
This core has a bunch of cool new features:
-MMU-v3: Variable Page Sz (4k, 8k, 16k), bigger J-TLB (128x4)
Shared Address Spaces (for sharing TLB entires in MMU)
-Caches: New Prog Model, Region Flush
-Insns: endian swap, load-locked/store-conditional, time-stamp-ctr
endif #ISA_ARCOMPACT
config ARC_CPU_HS
bool "ARC-HS"
depends on ISA_ARCV2
help
Support for ARC HS38x Cores based on ARCv2 ISA
The notable features are:
- SMP configurations of upto 4 core with coherency
- Optional L2 Cache and IO-Coherency
- Revised Interrupt Architecture (multiple priorites, reg banks,
auto stack switch, auto regfile save/restore)
- MMUv4 (PIPT dcache, Huge Pages)
- Instructions for
* 64bit load/store: LDD, STD
* Hardware assisted divide/remainder: DIV, REM
* Function prologue/epilogue: ENTER_S, LEAVE_S
* IRQ enable/disable: CLRI, SETI
* pop count: FFS, FLS
* SETcc, BMSKN, XBFU...
endchoice
config CPU_BIG_ENDIAN
bool "Enable Big Endian Mode"
default n
help
Build kernel for Big Endian Mode of ARC CPU
config SMP
bool "Symmetric Multi-Processing"
default n
select ARC_HAS_COH_CACHES if ISA_ARCV2
select ARC_MCIP if ISA_ARCV2
help
This enables support for systems with more than one CPU.
if SMP
config ARC_HAS_COH_CACHES
def_bool n
config ARC_HAS_REENTRANT_IRQ_LV2
def_bool n
config ARC_MCIP
bool "ARConnect Multicore IP (MCIP) Support "
depends on ISA_ARCV2
help
This IP block enables SMP in ARC-HS38 cores.
It provides for cross-core interrupts, multi-core debug
hardware semaphores, shared memory,....
config NR_CPUS
int "Maximum number of CPUs (2-4096)"
range 2 4096
default "4"
config ARC_SMP_HALT_ON_RESET
bool "Enable Halt-on-reset boot mode"
default y if ARC_UBOOT_SUPPORT
help
In SMP configuration cores can be configured as Halt-on-reset
or they could all start at same time. For Halt-on-reset, non
masters are parked until Master kicks them so they can start of
at designated entry point. For other case, all jump to common
entry point and spin wait for Master's signal.
endif #SMP
menuconfig ARC_CACHE
bool "Enable Cache Support"
default y
# if SMP, cache enabled ONLY if ARC implementation has cache coherency
depends on !SMP || ARC_HAS_COH_CACHES
if ARC_CACHE
config ARC_CACHE_LINE_SHIFT
int "Cache Line Length (as power of 2)"
range 5 7
default "6"
help
Starting with ARC700 4.9, Cache line length is configurable,
This option specifies "N", with Line-len = 2 power N
So line lengths of 32, 64, 128 are specified by 5,6,7, respectively
Linux only supports same line lengths for I and D caches.
config ARC_HAS_ICACHE
bool "Use Instruction Cache"
default y
config ARC_HAS_DCACHE
bool "Use Data Cache"
default y
config ARC_CACHE_PAGES
bool "Per Page Cache Control"
default y
depends on ARC_HAS_ICACHE || ARC_HAS_DCACHE
help
This can be used to over-ride the global I/D Cache Enable on a
per-page basis (but only for pages accessed via MMU such as
Kernel Virtual address or User Virtual Address)
TLB entries have a per-page Cache Enable Bit.
Note that Global I/D ENABLE + Per Page DISABLE works but corollary
Global DISABLE + Per Page ENABLE won't work
config ARC_CACHE_VIPT_ALIASING
bool "Support VIPT Aliasing D$"
depends on ARC_HAS_DCACHE && ISA_ARCOMPACT
default n
endif #ARC_CACHE
config ARC_HAS_ICCM
bool "Use ICCM"
help
Single Cycle RAMS to store Fast Path Code
default n
config ARC_ICCM_SZ
int "ICCM Size in KB"
default "64"
depends on ARC_HAS_ICCM
config ARC_HAS_DCCM
bool "Use DCCM"
help
Single Cycle RAMS to store Fast Path Data
default n
config ARC_DCCM_SZ
int "DCCM Size in KB"
default "64"
depends on ARC_HAS_DCCM
config ARC_DCCM_BASE
hex "DCCM map address"
default "0xA0000000"
depends on ARC_HAS_DCCM
choice
prompt "MMU Version"
default ARC_MMU_V3 if ARC_CPU_770
default ARC_MMU_V2 if ARC_CPU_750D
default ARC_MMU_V4 if ARC_CPU_HS
if ISA_ARCOMPACT
config ARC_MMU_V1
bool "MMU v1"
help
Orig ARC700 MMU
config ARC_MMU_V2
bool "MMU v2"
help
Fixed the deficiency of v1 - possible thrashing in memcpy sceanrio
when 2 D-TLB and 1 I-TLB entries index into same 2way set.
config ARC_MMU_V3
bool "MMU v3"
depends on ARC_CPU_770
help
Introduced with ARC700 4.10: New Features
Variable Page size (1k-16k), var JTLB size 128 x (2 or 4)
Shared Address Spaces (SASID)
endif
config ARC_MMU_V4
bool "MMU v4"
depends on ISA_ARCV2
endchoice
choice
prompt "MMU Page Size"
default ARC_PAGE_SIZE_8K
config ARC_PAGE_SIZE_8K
bool "8KB"
help
Choose between 8k vs 16k
config ARC_PAGE_SIZE_16K
bool "16KB"
depends on ARC_MMU_V3 || ARC_MMU_V4
config ARC_PAGE_SIZE_4K
bool "4KB"
depends on ARC_MMU_V3 || ARC_MMU_V4
endchoice
choice
prompt "MMU Super Page Size"
depends on ISA_ARCV2 && TRANSPARENT_HUGEPAGE
default ARC_HUGEPAGE_2M
config ARC_HUGEPAGE_2M
bool "2MB"
config ARC_HUGEPAGE_16M
bool "16MB"
endchoice
config NODES_SHIFT
int "Maximum NUMA Nodes (as a power of 2)"
default "1" if !DISCONTIGMEM
default "2" if DISCONTIGMEM
depends on NEED_MULTIPLE_NODES
---help---
Accessing memory beyond 1GB (with or w/o PAE) requires 2 memory
zones.
if ISA_ARCOMPACT
config ARC_COMPACT_IRQ_LEVELS
bool "ARCompact IRQ Priorities: High(2)/Low(1)"
default n
# Timer HAS to be high priority, for any other high priority config
select ARC_IRQ3_LV2
# if SMP, LV2 enabled ONLY if ARC implementation has LV2 re-entrancy
depends on !SMP || ARC_HAS_REENTRANT_IRQ_LV2
if ARC_COMPACT_IRQ_LEVELS
config ARC_IRQ3_LV2
bool
config ARC_IRQ5_LV2
bool
config ARC_IRQ6_LV2
bool
endif #ARC_COMPACT_IRQ_LEVELS
config ARC_FPU_SAVE_RESTORE
bool "Enable FPU state persistence across context switch"
default n
help
Double Precision Floating Point unit had dedictaed regs which
need to be saved/restored across context-switch.
Note that ARC FPU is overly simplistic, unlike say x86, which has
hardware pieces to allow software to conditionally save/restore,
based on actual usage of FPU by a task. Thus our implemn does
this for all tasks in system.
endif #ISA_ARCOMPACT
config ARC_CANT_LLSC
def_bool n
config ARC_HAS_LLSC
bool "Insn: LLOCK/SCOND (efficient atomic ops)"
default y
depends on !ARC_CANT_LLSC
config ARC_STAR_9000923308
bool "Workaround for llock/scond livelock"
default n
depends on ISA_ARCV2 && SMP && ARC_HAS_LLSC
config ARC_HAS_SWAPE
bool "Insn: SWAPE (endian-swap)"
default y
if ISA_ARCV2
config ARC_HAS_LL64
bool "Insn: 64bit LDD/STD"
help
Enable gcc to generate 64-bit load/store instructions
ISA mandates even/odd registers to allow encoding of two
dest operands with 2 possible source operands.
default y
config ARC_HAS_DIV_REM
bool "Insn: div, divu, rem, remu"
default y
config ARC_HAS_RTC
bool "Local 64-bit r/o cycle counter"
default n
depends on !SMP
config ARC_HAS_GFRC
bool "SMP synchronized 64-bit cycle counter"
default y
depends on SMP
config ARC_NUMBER_OF_INTERRUPTS
int "Number of interrupts"
range 8 240
default 32
help
This defines the number of interrupts on the ARCv2HS core.
It affects the size of vector table.
The initial 8 IRQs are fixed (Timer, ICI etc) and although configurable
in hardware, it keep things simple for Linux to assume they are always
present.
endif # ISA_ARCV2
endmenu # "ARC CPU Configuration"
config LINUX_LINK_BASE
hex "Linux Link Address"
default "0x80000000"
help
ARC700 divides the 32 bit phy address space into two equal halves
-Lower 2G (0 - 0x7FFF_FFFF ) is user virtual, translated by MMU
-Upper 2G (0x8000_0000 onwards) is untranslated, for kernel
Typically Linux kernel is linked at the start of untransalted addr,
hence the default value of 0x8zs.
However some customers have peripherals mapped at this addr, so
Linux needs to be scooted a bit.
If you don't know what the above means, leave this setting alone.
This needs to match memory start address specified in Device Tree
config HIGHMEM
bool "High Memory Support"
select DISCONTIGMEM
help
With ARC 2G:2G address split, only upper 2G is directly addressable by
kernel. Enable this to potentially allow access to rest of 2G and PAE
in future
config ARC_HAS_PAE40
bool "Support for the 40-bit Physical Address Extension"
default n
depends on ISA_ARCV2
help
Enable access to physical memory beyond 4G, only supported on
ARC cores with 40 bit Physical Addressing support
config ARCH_PHYS_ADDR_T_64BIT
def_bool ARC_HAS_PAE40
config ARCH_DMA_ADDR_T_64BIT
bool
config ARC_PLAT_NEEDS_PHYS_TO_DMA
bool
config ARC_KVADDR_SIZE
int "Kernel Virtaul Address Space size (MB)"
range 0 512
default "256"
help
The kernel address space is carved out of 256MB of translated address
space for catering to vmalloc, modules, pkmap, fixmap. This however may
not suffice vmalloc requirements of a 4K CPU EZChip system. So allow
this to be stretched to 512 MB (by extending into the reserved
kernel-user gutter)
config ARC_CURR_IN_REG
bool "Dedicate Register r25 for current_task pointer"
default y
help
This reserved Register R25 to point to Current Task in
kernel mode. This saves memory access for each such access
config ARC_EMUL_UNALIGNED
bool "Emulate unaligned memory access (userspace only)"
default N
select SYSCTL_ARCH_UNALIGN_NO_WARN
select SYSCTL_ARCH_UNALIGN_ALLOW
depends on ISA_ARCOMPACT
help
This enables misaligned 16 & 32 bit memory access from user space.
Use ONLY-IF-ABS-NECESSARY as it will be very slow and also can hide
potential bugs in code
config HZ
int "Timer Frequency"
default 100
config ARC_METAWARE_HLINK
bool "Support for Metaware debugger assisted Host access"
default n
help
This options allows a Linux userland apps to directly access
host file system (open/creat/read/write etc) with help from
Metaware Debugger. This can come in handy for Linux-host communication
when there is no real usable peripheral such as EMAC.
menuconfig ARC_DBG
bool "ARC debugging"
default y
if ARC_DBG
config ARC_DW2_UNWIND
bool "Enable DWARF specific kernel stack unwind"
default y
select KALLSYMS
help
Compiles the kernel with DWARF unwind information and can be used
to get stack backtraces.
If you say Y here the resulting kernel image will be slightly larger
but not slower, and it will give very useful debugging information.
If you don't debug the kernel, you can say N, but we may not be able
to solve problems without frame unwind information
config ARC_DBG_TLB_PARANOIA
bool "Paranoia Checks in Low Level TLB Handlers"
default n
config ARC_DBG_TLB_MISS_COUNT
bool "Profile TLB Misses"
default n
select DEBUG_FS
help
Counts number of I and D TLB Misses and exports them via Debugfs
The counters can be cleared via Debugfs as well
endif
config ARC_UBOOT_SUPPORT
bool "Support uboot arg Handling"
default n
help
ARC Linux by default checks for uboot provided args as pointers to
external cmdline or DTB. This however breaks in absence of uboot,
when booting from Metaware debugger directly, as the registers are
not zeroed out on reset by mdb and/or ARCv2 based cores. The bogus
registers look like uboot args to kernel which then chokes.
So only enable the uboot arg checking/processing if users are sure
of uboot being in play.
config ARC_BUILTIN_DTB_NAME
string "Built in DTB"
help
Set the name of the DTB to embed in the vmlinux binary
Leaving it blank selects the minimal "skeleton" dtb
source "kernel/Kconfig.preempt"
menu "Executable file formats"
source "fs/Kconfig.binfmt"
endmenu
endmenu # "ARC Architecture Configuration"
source "mm/Kconfig"
config FORCE_MAX_ZONEORDER
int "Maximum zone order"
default "12" if ARC_HUGEPAGE_16M
default "11"
source "net/Kconfig"
source "drivers/Kconfig"
menu "Bus Support"
config PCI
bool "PCI support" if MIGHT_HAVE_PCI
help
PCI is the name of a bus system, i.e., the way the CPU talks to
the other stuff inside your box. Find out if your board/platform
has PCI.
Note: PCIe support for Synopsys Device will be available only
when HAPS DX is configured with PCIe RC bitmap. If you have PCI,
say Y, otherwise N.
config PCI_SYSCALL
def_bool PCI
source "drivers/pci/Kconfig"
endmenu
source "fs/Kconfig"
source "arch/arc/Kconfig.debug"
source "security/Kconfig"
source "crypto/Kconfig"
source "lib/Kconfig"
source "kernel/power/Kconfig"
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