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  1. /*
  2.  * Copyright (C) 2005 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #include <console/kconsole.h>
  30. #include <console/console.h>
  31. #include <console/chardev.h>
  32. #include <print.h>
  33. #include <panic.h>
  34. #include <typedefs.h>
  35. #include <arch/types.h>
  36. #include <list.h>
  37. #include <arch.h>
  38. #include <func.h>
  39. #include <macros.h>
  40. #include <debug.h>
  41. #include <symtab.h>
  42.  
  43. #define MAX_CMDLINE 256
  44.  
  45. /** Simple kernel console.
  46.  *
  47.  * The console is realized by kernel thread kconsole.
  48.  * It doesn't understand any useful command on its own,
  49.  * but makes it possible for other kernel subsystems to
  50.  * register their own commands.
  51.  */
  52.  
  53. /** Locking.
  54.  *
  55.  * There is a list of cmd_info_t structures. This list
  56.  * is protected by cmd_lock spinlock. Note that specially
  57.  * the link elements of cmd_info_t are protected by
  58.  * this lock.
  59.  *
  60.  * Each cmd_info_t also has its own lock, which protects
  61.  * all elements thereof except the link element.
  62.  *
  63.  * cmd_lock must be acquired before any cmd_info lock.
  64.  * When locking two cmd info structures, structure with
  65.  * lower address must be locked first.
  66.  */
  67.  
  68. spinlock_t cmd_lock;    /**< Lock protecting command list. */
  69. link_t cmd_head;    /**< Command list. */
  70.  
  71. static cmd_info_t *parse_cmdline(char *cmdline, size_t len);
  72. static bool parse_argument(char *cmdline, size_t len, index_t *start, index_t *end);
  73.  
  74. /** Data and methods for 'help' command. */
  75. static int cmd_help(cmd_arg_t *argv);
  76. static cmd_info_t help_info = {
  77.     .name = "help",
  78.     .description = "List of supported commands.",
  79.     .func = cmd_help,
  80.     .argc = 0
  81. };
  82.  
  83. /** Data and methods for 'description' command. */
  84. static int cmd_desc(cmd_arg_t *argv);
  85. static void desc_help(void);
  86. static char desc_buf[MAX_CMDLINE+1];
  87. static cmd_arg_t desc_argv = {
  88.     .type = ARG_TYPE_STRING,
  89.     .buffer = desc_buf,
  90.     .len = sizeof(desc_buf)
  91. };
  92. static cmd_info_t desc_info = {
  93.     .name = "describe",
  94.     .description = "Describe specified command.",
  95.     .help = desc_help,
  96.     .func = cmd_desc,
  97.     .argc = 1,
  98.     .argv = &desc_argv
  99. };
  100.  
  101. /** Data and methods for 'symaddr' command. */
  102. static int cmd_symaddr(cmd_arg_t *argv);
  103. static char symaddr_buf[MAX_CMDLINE+1];
  104. static cmd_arg_t symaddr_argv = {
  105.     .type = ARG_TYPE_STRING,
  106.     .buffer = symaddr_buf,
  107.     .len = sizeof(symaddr_buf)
  108. };
  109. static cmd_info_t symaddr_info = {
  110.     .name = "symaddr",
  111.     .description = "Return symbol address.",
  112.     .func = cmd_symaddr,
  113.     .argc = 1,
  114.     .argv = &symaddr_argv
  115. };
  116.  
  117. /** Call0 - call function with no parameters */
  118. static char call0_buf[MAX_CMDLINE+1];
  119. static char carg1_buf[MAX_CMDLINE+1];
  120. static char carg2_buf[MAX_CMDLINE+1];
  121.  
  122. static int cmd_call0(cmd_arg_t *argv);
  123. static cmd_arg_t call0_argv = {
  124.     .type = ARG_TYPE_STRING,
  125.     .buffer = call0_buf,
  126.     .len = sizeof(call0_buf)
  127. };
  128. static cmd_info_t call0_info = {
  129.     .name = "call0",
  130.     .description = "call0 <function> -> call function().",
  131.     .func = cmd_call0,
  132.     .argc = 1,
  133.     .argv = &call0_argv
  134. };
  135.  
  136. static int cmd_call1(cmd_arg_t *argv);
  137. static cmd_arg_t call1_argv[] = {
  138.     {
  139.         .type = ARG_TYPE_STRING,
  140.         .buffer = call0_buf,
  141.         .len = sizeof(call0_buf)
  142.     },
  143.     {
  144.         .type = ARG_TYPE_VAR,
  145.         .buffer = carg1_buf,
  146.         .len = sizeof(carg1_buf)
  147.     }
  148. };
  149. static cmd_info_t call1_info = {
  150.     .name = "call1",
  151.     .description = "call1 <function> <arg1> -> call function(arg1).",
  152.     .func = cmd_call1,
  153.     .argc = 2,
  154.     .argv = call1_argv
  155. };
  156.  
  157. static int cmd_call2(cmd_arg_t *argv);
  158. static cmd_arg_t call2_argv[] = {
  159.     {
  160.         .type = ARG_TYPE_STRING,
  161.         .buffer = call0_buf,
  162.         .len = sizeof(call0_buf)
  163.     },
  164.     {
  165.         .type = ARG_TYPE_VAR,
  166.         .buffer = carg1_buf,
  167.         .len = sizeof(carg1_buf)
  168.     },
  169.     {
  170.         .type = ARG_TYPE_VAR,
  171.         .buffer = carg2_buf,
  172.         .len = sizeof(carg2_buf)
  173.     }
  174. };
  175. static cmd_info_t call2_info = {
  176.     .name = "call2",
  177.     .description = "call2 <function> <arg1> <arg2> -> call function(arg1,arg2).",
  178.     .func = cmd_call2,
  179.     .argc = 3,
  180.     .argv = call2_argv
  181. };
  182.  
  183.  
  184. /** Data and methods for 'halt' command. */
  185. static int cmd_halt(cmd_arg_t *argv);
  186. static cmd_info_t halt_info = {
  187.     .name = "halt",
  188.     .description = "Halt the kernel.",
  189.     .func = cmd_halt,
  190.     .argc = 0
  191. };
  192.  
  193. /** Initialize kconsole data structures. */
  194. void kconsole_init(void)
  195. {
  196.     spinlock_initialize(&cmd_lock, "kconsole_cmd");
  197.     list_initialize(&cmd_head);
  198.    
  199.     spinlock_initialize(&help_info.lock, "kconsole_help");
  200.     link_initialize(&help_info.link);
  201.     if (!cmd_register(&help_info))
  202.         panic("could not register command %s\n", help_info.name);
  203.  
  204.  
  205.     spinlock_initialize(&desc_info.lock, "kconsole_desc");
  206.     link_initialize(&desc_info.link);
  207.     if (!cmd_register(&desc_info))
  208.         panic("could not register command %s\n", desc_info.name);
  209.    
  210.     spinlock_initialize(&symaddr_info.lock, "kconsole_symaddr");
  211.     link_initialize(&symaddr_info.link);
  212.     if (!cmd_register(&symaddr_info))
  213.         panic("could not register command %s\n", symaddr_info.name);
  214.  
  215.     spinlock_initialize(&call0_info.lock, "kconsole_call0");
  216.     link_initialize(&call0_info.link);
  217.     if (!cmd_register(&call0_info))
  218.         panic("could not register command %s\n", call0_info.name);
  219.  
  220.     spinlock_initialize(&call1_info.lock, "kconsole_call1");
  221.     link_initialize(&call1_info.link);
  222.     if (!cmd_register(&call1_info))
  223.         panic("could not register command %s\n", call1_info.name);
  224.  
  225.  
  226.     spinlock_initialize(&call2_info.lock, "kconsole_call2");
  227.     link_initialize(&call2_info.link);
  228.     if (!cmd_register(&call2_info))
  229.         panic("could not register command %s\n", call2_info.name);
  230.    
  231.     spinlock_initialize(&halt_info.lock, "kconsole_halt");
  232.     link_initialize(&halt_info.link);
  233.     if (!cmd_register(&halt_info))
  234.         panic("could not register command %s\n", halt_info.name);
  235. }
  236.  
  237.  
  238. /** Register kconsole command.
  239.  *
  240.  * @param cmd Structure describing the command.
  241.  *
  242.  * @return 0 on failure, 1 on success.
  243.  */
  244. int cmd_register(cmd_info_t *cmd)
  245. {
  246.     ipl_t ipl;
  247.     link_t *cur;
  248.    
  249.     spinlock_lock(&cmd_lock);
  250.    
  251.     /*
  252.      * Make sure the command is not already listed.
  253.      */
  254.     for (cur = cmd_head.next; cur != &cmd_head; cur = cur->next) {
  255.         cmd_info_t *hlp;
  256.        
  257.         hlp = list_get_instance(cur, cmd_info_t, link);
  258.  
  259.         if (hlp == cmd) {
  260.             /* The command is already there. */
  261.             spinlock_unlock(&cmd_lock);
  262.             return 0;
  263.         }
  264.  
  265.         /* Avoid deadlock. */
  266.         if (hlp < cmd) {
  267.             spinlock_lock(&hlp->lock);
  268.             spinlock_lock(&cmd->lock);
  269.         } else {
  270.             spinlock_lock(&cmd->lock);
  271.             spinlock_lock(&hlp->lock);
  272.         }
  273.        
  274.         if ((strncmp(hlp->name, cmd->name, strlen(cmd->name)) == 0)) {
  275.             /* The command is already there. */
  276.             spinlock_unlock(&hlp->lock);
  277.             spinlock_unlock(&cmd->lock);
  278.             spinlock_unlock(&cmd_lock);
  279.             return 0;
  280.         }
  281.        
  282.         spinlock_unlock(&hlp->lock);
  283.         spinlock_unlock(&cmd->lock);
  284.     }
  285.    
  286.     /*
  287.      * Now the command can be added.
  288.      */
  289.     list_append(&cmd->link, &cmd_head);
  290.    
  291.     spinlock_unlock(&cmd_lock);
  292.     return 1;
  293. }
  294.  
  295. /** Kernel console managing thread.
  296.  *
  297.  * @param arg Not used.
  298.  */
  299. void kconsole(void *arg)
  300. {
  301.     char cmdline[MAX_CMDLINE+1];
  302.     cmd_info_t *cmd_info;
  303.     count_t len;
  304.  
  305.     if (!stdin) {
  306.         printf("%s: no stdin\n", __FUNCTION__);
  307.         return;
  308.     }
  309.    
  310.     while (true) {
  311.         printf("%s> ", __FUNCTION__);
  312.         if (!(len = gets(stdin, cmdline, sizeof(cmdline))))
  313.             continue;
  314.         cmdline[len] = '\0';
  315.         cmd_info = parse_cmdline(cmdline, len);
  316.         if (!cmd_info)
  317.             continue;
  318.         (void) cmd_info->func(cmd_info->argv);
  319.     }
  320. }
  321.  
  322. static int parse_int_arg(char *text, size_t len, __native *result)
  323. {
  324.     char symname[MAX_SYMBOL_NAME];
  325.     __address symaddr;
  326.     bool isaddr = false;
  327.     bool isptr = false;
  328.    
  329.     /* If we get a name, try to find it in symbol table */
  330.     if (text[0] < '0' | text[0] > '9') {
  331.         if (text[0] == '&') {
  332.             isaddr = true;
  333.             text++;len--;
  334.         } else if (text[0] == '*') {
  335.             isptr = true;
  336.             text++;len--;
  337.         }
  338.         strncpy(symname, text, min(len+1, MAX_SYMBOL_NAME));
  339.         symaddr = get_symbol_addr(symname);
  340.         if (!symaddr) {
  341.             printf("Symbol %s not found.\n",symname);
  342.             return -1;
  343.         }
  344.         if (symaddr == (__address) -1) {
  345.             printf("Duplicate symbol %s.\n",symname);
  346.             symtab_print_search(symname);
  347.             return -1;
  348.         }
  349.         if (isaddr)
  350.             *result = (__native)symaddr;
  351.         else if (isptr)
  352.             *result = **((__native **)symaddr);
  353.         else
  354.             *result = *((__native *)symaddr);
  355.     } else /* It's a number - convert it */
  356.         *result = atoi(text);
  357.     return 0;
  358. }
  359.  
  360. /** Parse command line.
  361.  *
  362.  * @param cmdline Command line as read from input device.
  363.  * @param len Command line length.
  364.  *
  365.  * @return Structure describing the command.
  366.  */
  367. cmd_info_t *parse_cmdline(char *cmdline, size_t len)
  368. {
  369.     index_t start = 0, end = 0;
  370.     cmd_info_t *cmd = NULL;
  371.     link_t *cur;
  372.     ipl_t ipl;
  373.     int i;
  374.    
  375.     if (!parse_argument(cmdline, len, &start, &end)) {
  376.         /* Command line did not contain alphanumeric word. */
  377.         return NULL;
  378.     }
  379.  
  380.     spinlock_lock(&cmd_lock);
  381.    
  382.     for (cur = cmd_head.next; cur != &cmd_head; cur = cur->next) {
  383.         cmd_info_t *hlp;
  384.        
  385.         hlp = list_get_instance(cur, cmd_info_t, link);
  386.         spinlock_lock(&hlp->lock);
  387.        
  388.         if (strncmp(hlp->name, &cmdline[start], (end - start) + 1) == 0) {
  389.             cmd = hlp;
  390.             break;
  391.         }
  392.        
  393.         spinlock_unlock(&hlp->lock);
  394.     }
  395.    
  396.     spinlock_unlock(&cmd_lock);
  397.    
  398.     if (!cmd) {
  399.         /* Unknown command. */
  400.         printf("Unknown command.\n");
  401.         return NULL;
  402.     }
  403.  
  404.     /* cmd == hlp is locked */
  405.    
  406.     /*
  407.      * The command line must be further analyzed and
  408.      * the parameters therefrom must be matched and
  409.      * converted to those specified in the cmd info
  410.      * structure.
  411.      */
  412.  
  413.     for (i = 0; i < cmd->argc; i++) {
  414.         char *buf;
  415.         start = end + 1;
  416.         if (!parse_argument(cmdline, len, &start, &end)) {
  417.             printf("Too few arguments.\n");
  418.             spinlock_unlock(&cmd->lock);
  419.             return NULL;
  420.         }
  421.        
  422.         switch (cmd->argv[i].type) {
  423.         case ARG_TYPE_STRING:
  424.                 buf = cmd->argv[i].buffer;
  425.                 strncpy(buf, (const char *) &cmdline[start], min((end - start) + 2, cmd->argv[i].len));
  426.             buf[min((end - start) + 1, cmd->argv[i].len - 1)] = '\0';
  427.             break;
  428.         case ARG_TYPE_INT:
  429.             if (parse_int_arg(cmdline+start, end-start+1,
  430.                       &cmd->argv[i].intval))
  431.                 return NULL;
  432.             break;
  433.         case ARG_TYPE_VAR:
  434.             if (start != end && cmdline[start] == '"' && cmdline[end] == '"') {
  435.                 buf = cmd->argv[i].buffer;
  436.                 strncpy(buf, (const char *) &cmdline[start+1],
  437.                     min((end-start), cmd->argv[i].len));
  438.                 buf[min((end - start), cmd->argv[i].len - 1)] = '\0';
  439.                 cmd->argv[i].intval = (__native) buf;
  440.                 cmd->argv[i].vartype = ARG_TYPE_STRING;
  441.             } else if (!parse_int_arg(cmdline+start, end-start+1,
  442.                          &cmd->argv[i].intval))
  443.                 cmd->argv[i].vartype = ARG_TYPE_INT;
  444.             else {
  445.                 printf("Unrecognized variable argument.\n");
  446.                 return NULL;
  447.             }
  448.             break;
  449.         case ARG_TYPE_INVALID:
  450.         default:
  451.             printf("invalid argument type\n");
  452.             return NULL;
  453.             break;
  454.         }
  455.     }
  456.    
  457.     start = end + 1;
  458.     if (parse_argument(cmdline, len, &start, &end)) {
  459.         printf("Too many arguments.\n");
  460.         spinlock_unlock(&cmd->lock);
  461.         return NULL;
  462.     }
  463.    
  464.     spinlock_unlock(&cmd->lock);
  465.     return cmd;
  466. }
  467.  
  468. /** Parse argument.
  469.  *
  470.  * Find start and end positions of command line argument.
  471.  *
  472.  * @param cmdline Command line as read from the input device.
  473.  * @param len Number of characters in cmdline.
  474.  * @param start On entry, 'start' contains pointer to the index
  475.  *        of first unprocessed character of cmdline.
  476.  *        On successful exit, it marks beginning of the next argument.
  477.  * @param end Undefined on entry. On exit, 'end' points to the last character
  478.  *        of the next argument.
  479.  *
  480.  * @return false on failure, true on success.
  481.  */
  482. bool parse_argument(char *cmdline, size_t len, index_t *start, index_t *end)
  483. {
  484.     int i;
  485.     bool found_start = false;
  486.    
  487.     ASSERT(start != NULL);
  488.     ASSERT(end != NULL);
  489.    
  490.     for (i = *start; i < len; i++) {
  491.         if (!found_start) {
  492.             if (is_white(cmdline[i]))
  493.                 (*start)++;
  494.             else
  495.                 found_start = true;
  496.         } else {
  497.             if (is_white(cmdline[i]))
  498.                 break;
  499.         }
  500.     }
  501.     *end = i - 1;
  502.  
  503.     return found_start;
  504. }
  505.  
  506.  
  507. /** List supported commands.
  508.  *
  509.  * @param argv Argument vector.
  510.  *
  511.  * @return 0 on failure, 1 on success.
  512.  */
  513. int cmd_help(cmd_arg_t *argv)
  514. {
  515.     link_t *cur;
  516.     ipl_t ipl;
  517.  
  518.     spinlock_lock(&cmd_lock);
  519.    
  520.     for (cur = cmd_head.next; cur != &cmd_head; cur = cur->next) {
  521.         cmd_info_t *hlp;
  522.        
  523.         hlp = list_get_instance(cur, cmd_info_t, link);
  524.         spinlock_lock(&hlp->lock);
  525.        
  526.         printf("%s - %s\n", hlp->name, hlp->description);
  527.  
  528.         spinlock_unlock(&hlp->lock);
  529.     }
  530.    
  531.     spinlock_unlock(&cmd_lock);
  532.  
  533.     return 1;
  534. }
  535.  
  536. /** Describe specified command.
  537.  *
  538.  * @param argv Argument vector.
  539.  *
  540.  * @return 0 on failure, 1 on success.
  541.  */
  542. int cmd_desc(cmd_arg_t *argv)
  543. {
  544.     link_t *cur;
  545.     ipl_t ipl;
  546.  
  547.     spinlock_lock(&cmd_lock);
  548.    
  549.     for (cur = cmd_head.next; cur != &cmd_head; cur = cur->next) {
  550.         cmd_info_t *hlp;
  551.        
  552.         hlp = list_get_instance(cur, cmd_info_t, link);
  553.         spinlock_lock(&hlp->lock);
  554.  
  555.         if (strncmp(hlp->name, (const char *) argv->buffer, strlen(hlp->name)) == 0) {
  556.             printf("%s - %s\n", hlp->name, hlp->description);
  557.             if (hlp->help)
  558.                 hlp->help();
  559.             spinlock_unlock(&hlp->lock);
  560.             break;
  561.         }
  562.  
  563.         spinlock_unlock(&hlp->lock);
  564.     }
  565.    
  566.     spinlock_unlock(&cmd_lock);
  567.  
  568.     return 1;
  569. }
  570.  
  571. /** Search symbol table */
  572. int cmd_symaddr(cmd_arg_t *argv)
  573. {
  574.     __address symaddr;
  575.     char *symbol;
  576.  
  577.     symtab_print_search(argv->buffer);
  578.    
  579.     return 1;
  580. }
  581.  
  582. /** Call function with zero parameters */
  583. int cmd_call0(cmd_arg_t *argv)
  584. {
  585.     __address symaddr;
  586.     char *symbol;
  587.     __native (*f)(void);
  588.  
  589.     symaddr = get_symbol_addr(argv->buffer);
  590.     if (!symaddr)
  591.         printf("Symbol %s not found.\n", argv->buffer);
  592.     else if (symaddr == (__address) -1) {
  593.         symtab_print_search(argv->buffer);
  594.         printf("Duplicate symbol, be more specific.\n");
  595.     } else {
  596.         symbol = get_symtab_entry(symaddr);
  597.         printf("Calling f(): 0x%p: %s\n", symaddr, symbol);
  598.         f =  (__native (*)(void)) symaddr;
  599.         printf("Result: 0x%X\n", f());
  600.     }
  601.    
  602.     return 1;
  603. }
  604.  
  605. /** Call function with one parameter */
  606. int cmd_call1(cmd_arg_t *argv)
  607. {
  608.     __address symaddr;
  609.     char *symbol;
  610.     __native (*f)(__native);
  611.     __native arg1 = argv[1].intval;
  612.  
  613.     symaddr = get_symbol_addr(argv->buffer);
  614.     if (!symaddr)
  615.         printf("Symbol %s not found.\n", argv->buffer);
  616.     else if (symaddr == (__address) -1) {
  617.         symtab_print_search(argv->buffer);
  618.         printf("Duplicate symbol, be more specific.\n");
  619.     } else {
  620.         symbol = get_symtab_entry(symaddr);
  621.         printf("Calling f(0x%x): 0x%p: %s\n", arg1, symaddr, symbol);
  622.         f =  (__native (*)(__native)) symaddr;
  623.         printf("Result: 0x%x\n", f(arg1));
  624.     }
  625.    
  626.     return 1;
  627. }
  628.  
  629. /** Call function with two parameters */
  630. int cmd_call2(cmd_arg_t *argv)
  631. {
  632.     __address symaddr;
  633.     char *symbol;
  634.     __native (*f)(__native,__native);
  635.     __native arg1 = argv[1].intval;
  636.     __native arg2 = argv[2].intval;
  637.  
  638.     symaddr = get_symbol_addr(argv->buffer);
  639.     if (!symaddr)
  640.         printf("Symbol %s not found.\n", argv->buffer);
  641.     else if (symaddr == (__address) -1) {
  642.         symtab_print_search(argv->buffer);
  643.         printf("Duplicate symbol, be more specific.\n");
  644.     } else {
  645.         symbol = get_symtab_entry(symaddr);
  646.         printf("Calling f(0x%x,0x%x): 0x%p: %s\n",
  647.                arg1, arg2, symaddr, symbol);
  648.         f =  (__native (*)(__native,__native)) symaddr;
  649.         printf("Result: 0x%x\n", f(arg1, arg2));
  650.     }
  651.    
  652.     return 1;
  653. }
  654.  
  655.  
  656. /** Print detailed description of 'describe' command. */
  657. void desc_help(void)
  658. {
  659.     printf("Syntax: describe command_name\n");
  660. }
  661.  
  662. /** Halt the kernel.
  663.  *
  664.  * @param argv Argument vector (ignored).
  665.  *
  666.  * @return 0 on failure, 1 on success (never returns).
  667.  */
  668. int cmd_halt(cmd_arg_t *argv)
  669. {
  670.     halt();
  671.     return 1;
  672. }
  673.