arch/sparc/kernel/setup_64.c

   1 /*
   2  *  linux/arch/sparc64/kernel/setup.c
   3  *
   4  *  Copyright (C) 1995,1996  David S. Miller (davem@caip.rutgers.edu)
   5  *  Copyright (C) 1997       Jakub Jelinek (jj@sunsite.mff.cuni.cz)
   6  */
   7
   8 #include <linux/errno.h>
   9 #include <linux/sched.h>
  10 #include <linux/kernel.h>
  11 #include <linux/mm.h>
  12 #include <linux/stddef.h>
  13 #include <linux/unistd.h>
  14 #include <linux/ptrace.h>
  15 #include <asm/smp.h>
  16 #include <linux/user.h>
  17 #include <linux/screen_info.h>
  18 #include <linux/delay.h>
  19 #include <linux/fs.h>
  20 #include <linux/seq_file.h>
  21 #include <linux/syscalls.h>
  22 #include <linux/kdev_t.h>
  23 #include <linux/major.h>
  24 #include <linux/string.h>
  25 #include <linux/init.h>
  26 #include <linux/inet.h>
  27 #include <linux/console.h>
  28 #include <linux/root_dev.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/cpu.h>
  31 #include <linux/initrd.h>
  32 #include <linux/module.h>
  33 #include <linux/start_kernel.h>
  34
  35 #include <asm/io.h>
  36 #include <asm/processor.h>
  37 #include <asm/oplib.h>
  38 #include <asm/page.h>
  39 #include <asm/pgtable.h>
  40 #include <asm/idprom.h>
  41 #include <asm/head.h>
  42 #include <asm/starfire.h>
  43 #include <asm/mmu_context.h>
  44 #include <asm/timer.h>
  45 #include <asm/sections.h>
  46 #include <asm/setup.h>
  47 #include <asm/mmu.h>
  48 #include <asm/ns87303.h>
  49 #include <asm/btext.h>
  50 #include <asm/elf.h>
  51 #include <asm/mdesc.h>
  52 #include <asm/cacheflush.h>
  53
  54 #ifdef CONFIG_IP_PNP
  55 #include <net/ipconfig.h>
  56 #endif
  57
  58 #include "entry.h"
  59 #include "kernel.h"
  60
  61 /* Used to synchronize accesses to NatSemi SUPER I/O chip configure
  62  * operations in asm/ns87303.h
  63  */
  64 DEFINE_SPINLOCK(ns87303_lock);
  65 EXPORT_SYMBOL(ns87303_lock);
  66
  67 struct screen_info screen_info = {
  68         0, 0,                   /* orig-x, orig-y */
  69         0,                      /* unused */
  70         0,                      /* orig-video-page */
  71         0,                      /* orig-video-mode */
  72         128,                    /* orig-video-cols */
  73         0, 0, 0,                /* unused, ega_bx, unused */
  74         54,                     /* orig-video-lines */
  75         0,                      /* orig-video-isVGA */
  76         16                      /* orig-video-points */
  77 };
  78
  79 static void
  80 prom_console_write(struct console *con, const char *s, unsigned n)
  81 {
  82         prom_write(s, n);
  83 }
  84
  85 /* Exported for mm/init.c:paging_init. */
  86 unsigned long cmdline_memory_size = 0;
  87
  88 static struct console prom_early_console = {
  89         .name =         "earlyprom",
  90         .write =        prom_console_write,
  91         .flags =        CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
  92         .index =        -1,
  93 };
  94
  95 /*
  96  * Process kernel command line switches that are specific to the
  97  * SPARC or that require special low-level processing.
  98  */
  99 static void __init process_switch(char c)
 100 {
 101         switch (c) {
 102         case 'd':
 103         case 's':
 104                 break;
 105         case 'h':
 106                 prom_printf("boot_flags_init: Halt!\n");
 107                 prom_halt();
 108                 break;
 109         case 'p':
 110                 prom_early_console.flags &= ~CON_BOOT;
 111                 break;
 112         case 'P':
 113                 /* Force UltraSPARC-III P-Cache on. */
 114                 if (tlb_type != cheetah) {
 115                         printk("BOOT: Ignoring P-Cache force option.\n");
 116                         break;
 117                 }
 118                 cheetah_pcache_forced_on = 1;
 119                 add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);
 120                 cheetah_enable_pcache();
 121                 break;
 122
 123         default:
 124                 printk("Unknown boot switch (-%c)\n", c);
 125                 break;
 126         }
 127 }
 128
 129 static void __init boot_flags_init(char *commands)
 130 {
 131         while (*commands) {
 132                 /* Move to the start of the next "argument". */
 133                 while (*commands && *commands == ' ')
 134                         commands++;
 135
 136                 /* Process any command switches, otherwise skip it. */
 137                 if (*commands == '\0')
 138                         break;
 139                 if (*commands == '-') {
 140                         commands++;
 141                         while (*commands && *commands != ' ')
 142                                 process_switch(*commands++);
 143                         continue;
 144                 }
 145                 if (!strncmp(commands, "mem=", 4))
 146                         cmdline_memory_size = memparse(commands + 4, &commands);
 147
 148                 while (*commands && *commands != ' ')
 149                         commands++;
 150         }
 151 }
 152
 153 extern unsigned short root_flags;
 154 extern unsigned short root_dev;
 155 extern unsigned short ram_flags;
 156 #define RAMDISK_IMAGE_START_MASK        0x07FF
 157 #define RAMDISK_PROMPT_FLAG             0x8000
 158 #define RAMDISK_LOAD_FLAG               0x4000
 159
 160 extern int root_mountflags;
 161
 162 char reboot_command[COMMAND_LINE_SIZE];
 163
 164 static struct pt_regs fake_swapper_regs = { { 0, }, 0, 0, 0, 0 };
 165
 166 static void __init per_cpu_patch(void)
 167 {
 168         struct cpuid_patch_entry *p;
 169         unsigned long ver;
 170         int is_jbus;
 171
 172         if (tlb_type == spitfire && !this_is_starfire)
 173                 return;
 174
 175         is_jbus = 0;
 176         if (tlb_type != hypervisor) {
 177                 __asm__ ("rdpr %%ver, %0" : "=r" (ver));
 178                 is_jbus = ((ver >> 32UL) == __JALAPENO_ID ||
 179                            (ver >> 32UL) == __SERRANO_ID);
 180         }
 181
 182         p = &__cpuid_patch;
 183         while (p < &__cpuid_patch_end) {
 184                 unsigned long addr = p->addr;
 185                 unsigned int *insns;
 186
 187                 switch (tlb_type) {
 188                 case spitfire:
 189                         insns = &p->starfire[0];
 190                         break;
 191                 case cheetah:
 192                 case cheetah_plus:
 193                         if (is_jbus)
 194                                 insns = &p->cheetah_jbus[0];
 195                         else
 196                                 insns = &p->cheetah_safari[0];
 197                         break;
 198                 case hypervisor:
 199                         insns = &p->sun4v[0];
 200                         break;
 201                 default:
 202                         prom_printf("Unknown cpu type, halting.\n");
 203                         prom_halt();
 204                 }
 205
 206                 *(unsigned int *) (addr +  0) = insns[0];
 207                 wmb();
 208                 __asm__ __volatile__("flush     %0" : : "r" (addr +  0));
 209
 210                 *(unsigned int *) (addr +  4) = insns[1];
 211                 wmb();
 212                 __asm__ __volatile__("flush     %0" : : "r" (addr +  4));
 213
 214                 *(unsigned int *) (addr +  8) = insns[2];
 215                 wmb();
 216                 __asm__ __volatile__("flush     %0" : : "r" (addr +  8));
 217
 218                 *(unsigned int *) (addr + 12) = insns[3];
 219                 wmb();
 220                 __asm__ __volatile__("flush     %0" : : "r" (addr + 12));
 221
 222                 p++;
 223         }
 224 }
 225
 226 void sun4v_patch_1insn_range(struct sun4v_1insn_patch_entry *start,
 227                              struct sun4v_1insn_patch_entry *end)
 228 {
 229         while (start < end) {
 230                 unsigned long addr = start->addr;
 231
 232                 *(unsigned int *) (addr +  0) = start->insn;
 233                 wmb();
 234                 __asm__ __volatile__("flush     %0" : : "r" (addr +  0));
 235
 236                 start++;
 237         }
 238 }
 239
 240 void sun4v_patch_2insn_range(struct sun4v_2insn_patch_entry *start,
 241                              struct sun4v_2insn_patch_entry *end)
 242 {
 243         while (start < end) {
 244                 unsigned long addr = start->addr;
 245
 246                 *(unsigned int *) (addr +  0) = start->insns[0];
 247                 wmb();
 248                 __asm__ __volatile__("flush     %0" : : "r" (addr +  0));
 249
 250                 *(unsigned int *) (addr +  4) = start->insns[1];
 251                 wmb();
 252                 __asm__ __volatile__("flush     %0" : : "r" (addr +  4));
 253
 254                 start++;
 255         }
 256 }
 257
 258 static void __init sun4v_patch(void)
 259 {
 260         extern void sun4v_hvapi_init(void);
 261
 262         if (tlb_type != hypervisor)
 263                 return;
 264
 265         sun4v_patch_1insn_range(&__sun4v_1insn_patch,
 266                                 &__sun4v_1insn_patch_end);
 267
 268         sun4v_patch_2insn_range(&__sun4v_2insn_patch,
 269                                 &__sun4v_2insn_patch_end);
 270
 271         sun4v_hvapi_init();
 272 }
 273
 274 static void __init popc_patch(void)
 275 {
 276         struct popc_3insn_patch_entry *p3;
 277         struct popc_6insn_patch_entry *p6;
 278
 279         p3 = &__popc_3insn_patch;
 280         while (p3 < &__popc_3insn_patch_end) {
 281                 unsigned long i, addr = p3->addr;
 282
 283                 for (i = 0; i < 3; i++) {
 284                         *(unsigned int *) (addr +  (i * 4)) = p3->insns[i];
 285                         wmb();
 286                         __asm__ __volatile__("flush     %0"
 287                                              : : "r" (addr +  (i * 4)));
 288                 }
 289
 290                 p3++;
 291         }
 292
 293         p6 = &__popc_6insn_patch;
 294         while (p6 < &__popc_6insn_patch_end) {
 295                 unsigned long i, addr = p6->addr;
 296
 297                 for (i = 0; i < 6; i++) {
 298                         *(unsigned int *) (addr +  (i * 4)) = p6->insns[i];
 299                         wmb();
 300                         __asm__ __volatile__("flush     %0"
 301                                              : : "r" (addr +  (i * 4)));
 302                 }
 303
 304                 p6++;
 305         }
 306 }
 307
 308 static void __init pause_patch(void)
 309 {
 310         struct pause_patch_entry *p;
 311
 312         p = &__pause_3insn_patch;
 313         while (p < &__pause_3insn_patch_end) {
 314                 unsigned long i, addr = p->addr;
 315
 316                 for (i = 0; i < 3; i++) {
 317                         *(unsigned int *) (addr +  (i * 4)) = p->insns[i];
 318                         wmb();
 319                         __asm__ __volatile__("flush     %0"
 320                                              : : "r" (addr +  (i * 4)));
 321                 }
 322
 323                 p++;
 324         }
 325 }
 326
 327 void __init start_early_boot(void)
 328 {
 329         int cpu;
 330
 331         check_if_starfire();
 332         per_cpu_patch();
 333         sun4v_patch();
 334
 335         cpu = hard_smp_processor_id();
 336         if (cpu >= NR_CPUS) {
 337                 prom_printf("Serious problem, boot cpu id (%d) >= NR_CPUS (%d)\n",
 338                             cpu, NR_CPUS);
 339                 prom_halt();
 340         }
 341         current_thread_info()->cpu = cpu;
 342
 343         prom_init_report();
 344         start_kernel();
 345 }
 346
 347 /* On Ultra, we support all of the v8 capabilities. */
 348 unsigned long sparc64_elf_hwcap = (HWCAP_SPARC_FLUSH | HWCAP_SPARC_STBAR |
 349                                    HWCAP_SPARC_SWAP | HWCAP_SPARC_MULDIV |
 350                                    HWCAP_SPARC_V9);
 351 EXPORT_SYMBOL(sparc64_elf_hwcap);
 352
 353 static const char *hwcaps[] = {
 354         "flush", "stbar", "swap", "muldiv", "v9",
 355         "ultra3", "blkinit", "n2",
 356
 357         /* These strings are as they appear in the machine description
 358          * 'hwcap-list' property for cpu nodes.
 359          */
 360         "mul32", "div32", "fsmuld", "v8plus", "popc", "vis", "vis2",
 361         "ASIBlkInit", "fmaf", "vis3", "hpc", "random", "trans", "fjfmau",
 362         "ima", "cspare", "pause", "cbcond",
 363 };
 364
 365 static const char *crypto_hwcaps[] = {
 366         "aes", "des", "kasumi", "camellia", "md5", "sha1", "sha256",
 367         "sha512", "mpmul", "montmul", "montsqr", "crc32c",
 368 };
 369
 370 void cpucap_info(struct seq_file *m)
 371 {
 372         unsigned long caps = sparc64_elf_hwcap;
 373         int i, printed = 0;
 374
 375         seq_puts(m, "cpucaps\t\t: ");
 376         for (i = 0; i < ARRAY_SIZE(hwcaps); i++) {
 377                 unsigned long bit = 1UL << i;
 378                 if (caps & bit) {
 379                         seq_printf(m, "%s%s",
 380                                    printed ? "," : "", hwcaps[i]);
 381                         printed++;
 382                 }
 383         }
 384         if (caps & HWCAP_SPARC_CRYPTO) {
 385                 unsigned long cfr;
 386
 387                 __asm__ __volatile__("rd %%asr26, %0" : "=r" (cfr));
 388                 for (i = 0; i < ARRAY_SIZE(crypto_hwcaps); i++) {
 389                         unsigned long bit = 1UL << i;
 390                         if (cfr & bit) {
 391                                 seq_printf(m, "%s%s",
 392                                            printed ? "," : "", crypto_hwcaps[i]);
 393                                 printed++;
 394                         }
 395                 }
 396         }
 397         seq_putc(m, '\n');
 398 }
 399
 400 static void __init report_one_hwcap(int *printed, const char *name)
 401 {
 402         if ((*printed) == 0)
 403                 printk(KERN_INFO "CPU CAPS: [");
 404         printk(KERN_CONT "%s%s",
 405                (*printed) ? "," : "", name);
 406         if (++(*printed) == 8) {
 407                 printk(KERN_CONT "]\n");
 408                 *printed = 0;
 409         }
 410 }
 411
 412 static void __init report_crypto_hwcaps(int *printed)
 413 {
 414         unsigned long cfr;
 415         int i;
 416
 417         __asm__ __volatile__("rd %%asr26, %0" : "=r" (cfr));
 418
 419         for (i = 0; i < ARRAY_SIZE(crypto_hwcaps); i++) {
 420                 unsigned long bit = 1UL << i;
 421                 if (cfr & bit)
 422                         report_one_hwcap(printed, crypto_hwcaps[i]);
 423         }
 424 }
 425
 426 static void __init report_hwcaps(unsigned long caps)
 427 {
 428         int i, printed = 0;
 429
 430         for (i = 0; i < ARRAY_SIZE(hwcaps); i++) {
 431                 unsigned long bit = 1UL << i;
 432                 if (caps & bit)
 433                         report_one_hwcap(&printed, hwcaps[i]);
 434         }
 435         if (caps & HWCAP_SPARC_CRYPTO)
 436                 report_crypto_hwcaps(&printed);
 437         if (printed != 0)
 438                 printk(KERN_CONT "]\n");
 439 }
 440
 441 static unsigned long __init mdesc_cpu_hwcap_list(void)
 442 {
 443         struct mdesc_handle *hp;
 444         unsigned long caps = 0;
 445         const char *prop;
 446         int len;
 447         u64 pn;
 448
 449         hp = mdesc_grab();
 450         if (!hp)
 451                 return 0;
 452
 453         pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "cpu");
 454         if (pn == MDESC_NODE_NULL)
 455                 goto out;
 456
 457         prop = mdesc_get_property(hp, pn, "hwcap-list", &len);
 458         if (!prop)
 459                 goto out;
 460
 461         while (len) {
 462                 int i, plen;
 463
 464                 for (i = 0; i < ARRAY_SIZE(hwcaps); i++) {
 465                         unsigned long bit = 1UL << i;
 466
 467                         if (!strcmp(prop, hwcaps[i])) {
 468                                 caps |= bit;
 469                                 break;
 470                         }
 471                 }
 472                 for (i = 0; i < ARRAY_SIZE(crypto_hwcaps); i++) {
 473                         if (!strcmp(prop, crypto_hwcaps[i]))
 474                                 caps |= HWCAP_SPARC_CRYPTO;
 475                 }
 476
 477                 plen = strlen(prop) + 1;
 478                 prop += plen;
 479                 len -= plen;
 480         }
 481
 482 out:
 483         mdesc_release(hp);
 484         return caps;
 485 }
 486
 487 /* This yields a mask that user programs can use to figure out what
 488  * instruction set this cpu supports.
 489  */
 490 static void __init init_sparc64_elf_hwcap(void)
 491 {
 492         unsigned long cap = sparc64_elf_hwcap;
 493         unsigned long mdesc_caps;
 494
 495         if (tlb_type == cheetah || tlb_type == cheetah_plus)
 496                 cap |= HWCAP_SPARC_ULTRA3;
 497         else if (tlb_type == hypervisor) {
 498                 if (sun4v_chip_type == SUN4V_CHIP_NIAGARA1 ||
 499                     sun4v_chip_type == SUN4V_CHIP_NIAGARA2 ||
 500                     sun4v_chip_type == SUN4V_CHIP_NIAGARA3 ||
 501                     sun4v_chip_type == SUN4V_CHIP_NIAGARA4 ||
 502                     sun4v_chip_type == SUN4V_CHIP_NIAGARA5 ||
 503                     sun4v_chip_type == SUN4V_CHIP_SPARC_M6 ||
 504                     sun4v_chip_type == SUN4V_CHIP_SPARC_M7 ||
 505                     sun4v_chip_type == SUN4V_CHIP_SPARC64X)
 506                         cap |= HWCAP_SPARC_BLKINIT;
 507                 if (sun4v_chip_type == SUN4V_CHIP_NIAGARA2 ||
 508                     sun4v_chip_type == SUN4V_CHIP_NIAGARA3 ||
 509                     sun4v_chip_type == SUN4V_CHIP_NIAGARA4 ||
 510                     sun4v_chip_type == SUN4V_CHIP_NIAGARA5 ||
 511                     sun4v_chip_type == SUN4V_CHIP_SPARC_M6 ||
 512                     sun4v_chip_type == SUN4V_CHIP_SPARC_M7 ||
 513                     sun4v_chip_type == SUN4V_CHIP_SPARC64X)
 514                         cap |= HWCAP_SPARC_N2;
 515         }
 516
 517         cap |= (AV_SPARC_MUL32 | AV_SPARC_DIV32 | AV_SPARC_V8PLUS);
 518
 519         mdesc_caps = mdesc_cpu_hwcap_list();
 520         if (!mdesc_caps) {
 521                 if (tlb_type == spitfire)
 522                         cap |= AV_SPARC_VIS;
 523                 if (tlb_type == cheetah || tlb_type == cheetah_plus)
 524                         cap |= AV_SPARC_VIS | AV_SPARC_VIS2;
 525                 if (tlb_type == cheetah_plus) {
 526                         unsigned long impl, ver;
 527
 528                         __asm__ __volatile__("rdpr %%ver, %0" : "=r" (ver));
 529                         impl = ((ver >> 32) & 0xffff);
 530                         if (impl == PANTHER_IMPL)
 531                                 cap |= AV_SPARC_POPC;
 532                 }
 533                 if (tlb_type == hypervisor) {
 534                         if (sun4v_chip_type == SUN4V_CHIP_NIAGARA1)
 535                                 cap |= AV_SPARC_ASI_BLK_INIT;
 536                         if (sun4v_chip_type == SUN4V_CHIP_NIAGARA2 ||
 537                             sun4v_chip_type == SUN4V_CHIP_NIAGARA3 ||
 538                             sun4v_chip_type == SUN4V_CHIP_NIAGARA4 ||
 539                             sun4v_chip_type == SUN4V_CHIP_NIAGARA5 ||
 540                             sun4v_chip_type == SUN4V_CHIP_SPARC_M6 ||
 541                             sun4v_chip_type == SUN4V_CHIP_SPARC_M7 ||
 542                             sun4v_chip_type == SUN4V_CHIP_SPARC64X)
 543                                 cap |= (AV_SPARC_VIS | AV_SPARC_VIS2 |
 544                                         AV_SPARC_ASI_BLK_INIT |
 545                                         AV_SPARC_POPC);
 546                         if (sun4v_chip_type == SUN4V_CHIP_NIAGARA3 ||
 547                             sun4v_chip_type == SUN4V_CHIP_NIAGARA4 ||
 548                             sun4v_chip_type == SUN4V_CHIP_NIAGARA5 ||
 549                             sun4v_chip_type == SUN4V_CHIP_SPARC_M6 ||
 550                             sun4v_chip_type == SUN4V_CHIP_SPARC_M7 ||
 551                             sun4v_chip_type == SUN4V_CHIP_SPARC64X)
 552                                 cap |= (AV_SPARC_VIS3 | AV_SPARC_HPC |
 553                                         AV_SPARC_FMAF);
 554                 }
 555         }
 556         sparc64_elf_hwcap = cap | mdesc_caps;
 557
 558         report_hwcaps(sparc64_elf_hwcap);
 559
 560         if (sparc64_elf_hwcap & AV_SPARC_POPC)
 561                 popc_patch();
 562         if (sparc64_elf_hwcap & AV_SPARC_PAUSE)
 563                 pause_patch();
 564 }
 565
 566 void __init setup_arch(char **cmdline_p)
 567 {
 568         /* Initialize PROM console and command line. */
 569         *cmdline_p = prom_getbootargs();
 570         strlcpy(boot_command_line, *cmdline_p, COMMAND_LINE_SIZE);
 571         parse_early_param();
 572
 573         boot_flags_init(*cmdline_p);
 574 #ifdef CONFIG_EARLYFB
 575         if (btext_find_display())
 576 #endif
 577                 register_console(&prom_early_console);
 578
 579         if (tlb_type == hypervisor)
 580                 printk("ARCH: SUN4V\n");
 581         else
 582                 printk("ARCH: SUN4U\n");
 583
 584 #ifdef CONFIG_DUMMY_CONSOLE
 585         conswitchp = &dummy_con;
 586 #endif
 587
 588         idprom_init();
 589
 590         if (!root_flags)
 591                 root_mountflags &= ~MS_RDONLY;
 592         ROOT_DEV = old_decode_dev(root_dev);
 593 #ifdef CONFIG_BLK_DEV_RAM
 594         rd_image_start = ram_flags & RAMDISK_IMAGE_START_MASK;
 595         rd_prompt = ((ram_flags & RAMDISK_PROMPT_FLAG) != 0);
 596         rd_doload = ((ram_flags & RAMDISK_LOAD_FLAG) != 0);
 597 #endif
 598
 599         task_thread_info(&init_task)->kregs = &fake_swapper_regs;
 600
 601 #ifdef CONFIG_IP_PNP
 602         if (!ic_set_manually) {
 603                 phandle chosen = prom_finddevice("/chosen");
 604                 u32 cl, sv, gw;
 605
 606                 cl = prom_getintdefault (chosen, "client-ip", 0);
 607                 sv = prom_getintdefault (chosen, "server-ip", 0);
 608                 gw = prom_getintdefault (chosen, "gateway-ip", 0);
 609                 if (cl && sv) {
 610                         ic_myaddr = cl;
 611                         ic_servaddr = sv;
 612                         if (gw)
 613                                 ic_gateway = gw;
 614 #if defined(CONFIG_IP_PNP_BOOTP) || defined(CONFIG_IP_PNP_RARP)
 615                         ic_proto_enabled = 0;
 616 #endif
 617                 }
 618         }
 619 #endif
 620
 621         /* Get boot processor trap_block[] setup.  */
 622         init_cur_cpu_trap(current_thread_info());
 623
 624         paging_init();
 625         init_sparc64_elf_hwcap();
 626 }
 627
 628 extern int stop_a_enabled;
 629
 630 void sun_do_break(void)
 631 {
 632         if (!stop_a_enabled)
 633                 return;
 634
 635         prom_printf("\n");
 636         flush_user_windows();
 637
 638         prom_cmdline();
 639 }
 640 EXPORT_SYMBOL(sun_do_break);
 641
 642 int stop_a_enabled = 1;
 643 EXPORT_SYMBOL(stop_a_enabled);