Index: kernel/generic/include/cpu/cpu_mask.h
===================================================================
--- kernel/generic/include/cpu/cpu_mask.h	(revision c79800f66d9e4a8fc017a7022699c3e34b795b26)
+++ kernel/generic/include/cpu/cpu_mask.h	(revision c79800f66d9e4a8fc017a7022699c3e34b795b26)
@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2012 Adam Hraska
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup generic
+ * @{
+ */
+/** @file
+ */
+#ifndef KERN_CPU_CPU_MASK_H_
+#define KERN_CPU_CPU_MASK_H_
+
+#include <cpu.h>
+#include <config.h>
+#include <lib/memfnc.h>
+
+/** Iterates over all cpu id's whose bit is included in the cpu mask. 
+ * 
+ * Example usage:
+ * @code
+ * DEFINE_CPU_MASK(cpu_mask);
+ * cpu_mask_active(&cpu_mask);
+ * 
+ * cpu_mask_for_each(cpu_mask, cpu_id) {
+ *     printf("Cpu with logical id %u is active.\n", cpu_id);
+ * }
+ * @endcode
+ */
+#define cpu_mask_for_each(mask, cpu_id) \
+	for (unsigned int (cpu_id) = 0; (cpu_id) < config.cpu_count; ++(cpu_id)) \
+		if (cpu_mask_is_set(&(mask), (cpu_id))) 
+
+/** Allocates a cpu_mask_t on stack. */
+#define DEFINE_CPU_MASK(cpu_mask) \
+	cpu_mask_t *(cpu_mask) = (cpu_mask_t*) alloca(cpu_mask_size())
+
+/** If used with DEFINE_CPU_MASK, the mask is large enough for all detected cpus.*/
+typedef struct cpu_mask {
+	unsigned int mask[1];
+} cpu_mask_t;
+
+
+extern size_t cpu_mask_size(void);
+extern void cpu_mask_active(cpu_mask_t *);
+extern void cpu_mask_all(cpu_mask_t *);
+extern void cpu_mask_none(cpu_mask_t *);
+extern void cpu_mask_set(cpu_mask_t *, unsigned int);
+extern void cpu_mask_reset(cpu_mask_t *, unsigned int);
+extern bool cpu_mask_is_set(cpu_mask_t *, unsigned int);
+extern bool cpu_mask_is_none(cpu_mask_t *);
+
+#endif /* KERN_CPU_CPU_MASK_H_ */ 
+
+/** @}
+ */
Index: kernel/generic/include/lib/memfnc.h
===================================================================
--- kernel/generic/include/lib/memfnc.h	(revision e0c80f665c3acae1820d84306689330477ca7c75)
+++ kernel/generic/include/lib/memfnc.h	(revision c79800f66d9e4a8fc017a7022699c3e34b795b26)
@@ -41,4 +41,6 @@
 extern void *memcpy(void *, const void *, size_t);
 
+#define alloca(size) __builtin_alloca((size))
+
 #endif