Why have a separate CONFIG_INIT_SWAPON when we already have CONFIG_SWAPONOFF?

diff --git a/init/Config.in b/init/Config.in
index a3584aa..91d990c 100644 (file)
--- a/init/Config.in
+++ b/init/Config.in
@@ -35,14 +35,6 @@ config CONFIG_FEATURE_INIT_COREDUMPS
          core file sizes.  If this option is disabled, processes
          will not generate any core files.
 
-config CONFIG_FEATURE_INIT_SWAPON
-       bool "  Should init run swapon if short on memory?"
-       default y
-       depends on CONFIG_INIT
-       help
-         If the system has less than one megabyte of total memory, init
-         will run '/sbin/swapon -a' to add swap memory.
-
 config CONFIG_FEATURE_INIT_SCTTY
        bool "  Support running commands with a controlling-tty?"
        default n

diff --git a/init/init.c b/init/init.c
index 7656bf3..058a47a 100644 (file)
--- a/init/init.c
+++ b/init/init.c
@@ -308,37 +308,6 @@ static void set_term(int fd)
        tcsetattr(fd, TCSANOW, &tty);
 }
 
-#ifdef CONFIG_FEATURE_INIT_SWAPON
-/* How much memory does this machine have?
-   Units are kBytes to avoid overflow on 4GB machines */
-static unsigned int check_free_memory(void)
-{
-       struct sysinfo info;
-       unsigned int result, u, s = 10;
-
-       if (sysinfo(&info) != 0) {
-               bb_perror_msg("Error checking free memory");
-               return -1;
-       }
-
-       /* Kernels 2.0.x and 2.2.x return info.mem_unit==0 with values in bytes.
-        * Kernels 2.4.0 return info.mem_unit in bytes. */
-       u = info.mem_unit;
-       if (u == 0)
-               u = 1;
-       while ((u & 1) == 0 && s > 0) {
-               u >>= 1;
-               s--;
-       }
-       result = (info.totalram >> s) + (info.totalswap >> s);
-       if (((unsigned long long)result * (unsigned long long)u) > UINT_MAX) {
-               return(UINT_MAX);
-       } else {
-               return(result * u);
-       }
-}
-#endif /* CONFIG_FEATURE_INIT_SWAPON */
-
 static void console_init(void)
 {
        int fd;
@@ -918,38 +887,6 @@ static void delete_init_action(struct init_action *action)
        }
 }
 
-#ifdef CONFIG_FEATURE_INIT_SWAPON
-/* Make sure there is enough memory to do something useful. *
- * Calls "swapon -a" if needed so be sure /etc/fstab is present... */
-static void check_memory(void)
-{
-       struct stat statBuf;
-
-       if (check_free_memory() > 1000)
-               return;
-
-#if !defined(__UCLIBC__) || defined(__ARCH_HAS_MMU__)
-       if (stat("/etc/fstab", &statBuf) == 0) {
-               /* swapon -a requires /proc typically */
-               new_init_action(SYSINIT, "/bin/mount -t proc proc /proc", "");
-               /* Try to turn on swap */
-               new_init_action(SYSINIT, "/sbin/swapon -a", "");
-               run_actions(SYSINIT);   /* wait and removing */
-               if (check_free_memory() < 1000)
-                       goto goodnight;
-       } else
-               goto goodnight;
-       return;
-#endif
-
-  goodnight:
-       message(CONSOLE, "Sorry, your computer does not have enough memory.");
-       loop_forever();
-}
-#else
-# define check_memory()
-#endif /* CONFIG_FEATURE_INIT_SWAPON */
-
 /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
  * then parse_inittab() simply adds in some default
  * actions(i.e., runs INIT_SCRIPT and then starts a pair
@@ -1149,7 +1086,20 @@ extern int init_main(int argc, char **argv)
        message(MAYBE_CONSOLE | LOG, "init started:  %s", bb_msg_full_version);
 
        /* Make sure there is enough memory to do something useful. */
-       check_memory();
+       if (ENABLE_SWAPONOFF) {
+               struct sysinfo info;
+
+               if (!sysinfo(&info) &&
+                       (info.mem_unit ? : 1) * (long long)info.totalram < MEGABYTE)
+               {
+                       message(CONSOLE,"Low memory: forcing swapon.");
+                       /* swapon -a requires /proc typically */
+                       new_init_action(SYSINIT, "/bin/mount -t proc proc /proc", "");
+                       /* Try to turn on swap */
+                       new_init_action(SYSINIT, "/sbin/swapon -a", "");
+                       run_actions(SYSINIT);   /* wait and removing */
+               }
+       }
 
        /* Check if we are supposed to be in single user mode */
        if (argc > 1 && (!strcmp(argv[1], "single") ||