diff --git a/src/Makefile b/src/Makefile
index 4c61f15..79c8836 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -8,13 +8,15 @@
 #----------------------------------------------------------------------------#
 
 CCNAME="/opt/cross-cc/bin/x86_64-elf-gcc"
+CC2NAME=gcc # compiler for testing
 CLDSCR=-T kernel.ld
 CWARNS= -pedantic -Wall -Wextra -Werror
 CFLAGS=-nostdlib -ffreestanding -mcmodel=large -mno-red-zone -mno-mmx -mno-sse -mno-sse2
-CDEFINES=-D_KALEID_KERNEL
 CINCLUDES=-I./kaleid
+CDEFINES=
 
-CC=$(CCNAME) $(CWARNS) $(CLDSCR) $(CFLAGS) $(CDEFINES) $(CINCLUDES)
+CC=$(CCNAME) $(CWARNS) $(CFLAGS) $(CDEFINES) $(CINCLUDES)
+KCC=$(CC) -D_KALEID_KERNEL
 
 ASM=nasm
 ASMFLAGS=
@@ -27,6 +29,7 @@ BOOTDIR=boot
 COMMDIR=kaleid/common
 KERNDIR=kaleid/kernel
 SYSTDIR=kaleid/system
+LINXDIR=kaleid/linux
 
 all: bootloader
 
@@ -53,44 +56,40 @@ testing: bootloader pseudo_kern
 # COMMON MAKEFILE
 
 COBJDIR=$(OBJDIR)/$(COMMDIR)
+LOBJDIR=$(OBJDIR)/$(LINXDIR)
 
 COMMDEPS=$(COMMDIR)/common.h $(COMMDIR)/assert.h $(COMMDIR)/atomic.h $(COMMDIR)/config.h \
 			$(COMMDIR)/status.h
 
-COBJECTS=$(COBJDIR)/lib/string.o $(COBJDIR)/lib/status.o
+COMMOBJS=$(COBJDIR)/lib/string.o $(COBJDIR)/lib/status.o
 
-common: common.lib.string.c common.lib.status.c
+common: $(COMMDEPS) $(COMMDIR)/lib/string.c $(COMMDIR)/lib/status.c
+	$(KCC) -c $(COMMDIR)/lib/string.c -o $(COBJDIR)/lib/string.o
+	$(KCC) -c $(COMMDIR)/lib/status.c -o $(COBJDIR)/lib/status.o
 
-common.lib.string.c: $(COMMDIR)/lib/string.c $(COMMDEPS)
-	$(CC) -c $(COMMDIR)/lib/string.c -o $(COBJDIR)/lib/string.o
+CCC=$(CC2NAME) $(CWARNS) $(CDEFINES) $(CINCLUDES) 
 
-common.lib.status.c: $(COMMDIR)/lib/status.c $(COMMDEPS)
-	$(CC) -c $(COMMDIR)/lib/status.c -o $(COBJDIR)/lib/status.o
+common-test:
+	$(CCC) -c $(COMMDIR)/lib/string.c -o $(COBJDIR)/lib/string.o
+	$(CCC) -c $(COMMDIR)/lib/status.c -o $(COBJDIR)/lib/status.o
+	$(CCC) -c $(LINXDIR)/test-common.c -o $(LOBJDIR)/test-common.o
+	$(CCC) $(COMMOBJS) $(LOBJDIR)/test-common.o -o $(BINDIR)/kaleid-common.elf
 
 #----------------------------------------------------------------------------#
 # KERNEL MAKEFILE
 
 KOBJDIR=$(OBJDIR)/$(KERNDIR)
 
-KERNDEPS=$(COMMDEPS) $(KERNDIR)/init.h $(KERNDIR)/io/terminal.h $(KERNDIR)/io/ports.h $(KERNDIR)/ke/panic.h
+KERNDEPS=common $(KERNDIR)/init.h $(KERNDIR)/io/terminal.h $(KERNDIR)/io/ports.h $(KERNDIR)/ke/panic.h
+KERNSRCS=$(KERNDIR)/init.c $(KERNDIR)/ke/panic.c $(KERNDIR)/io/ports.c $(KERNDIR)/io/terminal.c
+KERNOBJS=$(KOBJDIR)/init.o $(KOBJDIR)/ke/panic.o $(KOBJDIR)/io/ports.o $(KOBJDIR)/io/terminal.o
 
-kernel: common kernel.io.terminal.c kernel.init.c kernel.io.ports.c kernel.ke.panic.c
-	$(CC) -o $(BINDIR)/kaleid-kernel.elf \
-			$(COBJECTS) $(KOBJDIR)/init.o $(KOBJDIR)/ke/panic.o \
-			$(KOBJDIR)/io/terminal.o $(KOBJDIR)/io/ports.o
-
-
-kernel.init.c: $(KERNDIR)/init.c $(KERNDEPS)
-	$(CC) -c $(KERNDIR)/init.c -o $(KOBJDIR)/init.o
-
-kernel.io.ports.c: $(KERNDIR)/io/ports.c $(KERNDEPS)
-	$(CC) -c $(KERNDIR)/io/ports.c -o $(KOBJDIR)/io/ports.o
-
-kernel.io.terminal.c: $(KERNDIR)/io/terminal.c $(KERNDEPS)
-	$(CC) -c $(KERNDIR)/io/terminal.c -o $(KOBJDIR)/io/terminal.o
-
-kernel.ke.panic.c: $(KERNDIR)/ke/panic.c $(KERNDEPS)
-	$(CC) -c $(KERNDIR)/ke/panic.c -o $(KOBJDIR)/ke/panic.o
+kernel: common $(KERNSRCS)
+	$(KCC) -c $(KERNDIR)/init.c         -o $(KOBJDIR)/init.o
+	$(KCC) -c $(KERNDIR)/ke/panic.c     -o $(KOBJDIR)/ke/panic.o
+	$(KCC) -c $(KERNDIR)/io/ports.c     -o $(KOBJDIR)/io/ports.o
+	$(KCC) -c $(KERNDIR)/io/terminal.c  -o $(KOBJDIR)/io/terminal.o
+	$(KCC) $(CLDSCR) $(COMMOBJS) $(KERNOBJS) -o $(BINDIR)/kaleid-kernel.elf
 
 #----------------------------------------------------------------------------#
 
diff --git a/src/kaleid/common/assert.h b/src/kaleid/common/assert.h
index 98aadcc..da80ace 100644
--- a/src/kaleid/common/assert.h
+++ b/src/kaleid/common/assert.h
@@ -10,19 +10,18 @@
 #ifndef _KALCOMM_ASSERT_H
 #define _KALCOMM_ASSERT_H
 
+#ifndef _KALCOMM_COMMON_H
+#error "don't include common/types.h without common/common.h"
+#endif
+
+#ifdef _OSK_SOURCE
+
 #if !defined(_NO_DEBUG) && !defined(NDEBUG)
 
 // uses panic() in kernel, abort() in system
 noreturn void ___assert_handler(const char *, const char *, int, const char *);
 
-#define assert(x) do{if(!(x))___assert_handler(#x, __FILE__, __LINE__, __func__);}while(0);
-
-/*
-#define assert_never_used(x) do{static bool __##x##_init = FALSE; \
-        assert(__##x##_init == FALSE); __##x##_init = TRUE;}while(0);
-
-#define assert_used_once(x) do{static bool __##x##_init; assert(__##x##_init == TRUE);} while(0);
-*/
+#define assert(x) do{if(unlikely(!(x)))___assert_handler(#x, __FILE__, __LINE__, __func__);}while(0);
 
 #else // not debugging
 
@@ -35,8 +34,16 @@ noreturn void ___assert_handler(const char *, const char *, int, const char *);
 #endif
 
 #define assert(x)
-#define assert_used_once(x)
-#define assert_never_used(x)
+
+#endif
+
+#else // !defined(_OSK_SOURCE)
+
+#if defined(_NO_DEBUG) && !defined(NDEBUG)
+#define NDEBUG 1
+#endif
+
+#include <assert.h>
 
 #endif
 
diff --git a/src/kaleid/common/atomic.h b/src/kaleid/common/atomic.h
index bb4bf04..a1daef3 100644
--- a/src/kaleid/common/atomic.h
+++ b/src/kaleid/common/atomic.h
@@ -10,6 +10,10 @@
 #ifndef _KALCOMM_ATOMIC_H
 #define _KALCOMM_ATOMIC_H
 
+#ifndef _KALCOMM_COMMON_H
+#error "don't include common/types.h without common/common.h"
+#endif
+
 // atomic_t defined in common/types.h
 
 #ifdef _KALEID_KERNEL
diff --git a/src/kaleid/common/common.h b/src/kaleid/common/common.h
index 9c06922..9c9dd6a 100644
--- a/src/kaleid/common/common.h
+++ b/src/kaleid/common/common.h
@@ -7,28 +7,39 @@
 //  Desc:       Standard include file for both kernel/ and system/            //
 //----------------------------------------------------------------------------//
 
-
 #ifndef _KALCOMM_COMMON_H
 #define _KALCOMM_COMMON_H
 
-#define true 1
-#define TRUE 1
-#define YES  1
+#if !defined(_OSK_SOURCE) && (defined(_KALEID_KERNEL) || defined(_KALEID_SYSTEM))
+#define _OSK_SOURCE 1
+#endif
 
-#define false 0
-#define FALSE 0
-#define NO    0
+#if !defined(TRUE) && !defined(FALSE)
+#   define TRUE 1
+#   define FALSE 0
+#endif
 
-#define NULL ((void*)0)
+#ifdef _OSK_SOURCE
+#   define YES   1
+#   define NO    0
+#endif
 
-#define PACKED __attribute__((packed))
-#define noreturn __attribute__((noreturn))
+#ifndef NULL
+#   define NULL ((void*)0)
+#endif
 
-#define THROWS(...)
-#define ERRS(...)
+#ifndef PACKED
+#   define     PACKED __attribute__((packed))
+#endif
 
-#define likely(x)   __builtin_expect((x), 1)
-#define unlikely(x) __builtin_expect((x), 0)
+#ifndef noreturn
+#   define     noreturn __attribute__((noreturn))
+#endif
+
+#if !defined(likely) && !defined(unlikely)
+#   define likely(x)   __builtin_expect((x), 1)
+#   define unlikely(x) __builtin_expect((x), 0)
+#endif
 
 #include "common/types.h"
 #include "common/config.h"
diff --git a/src/kaleid/common/convert.h b/src/kaleid/common/convert.h
new file mode 100644
index 0000000..737f016
--- /dev/null
+++ b/src/kaleid/common/convert.h
@@ -0,0 +1,24 @@
+//----------------------------------------------------------------------------//
+//                           GNU GPL OS/K                                     //
+//                                                                            //
+//  Authors:    spectral`                                                     //
+//              NeoX                                                          //
+//                                                                            //
+//  Desc:       Conversion utilities                                          //
+//----------------------------------------------------------------------------//
+
+#ifndef _KALCOMM_CONVERT_H
+#define _KALCOMM_CONVERT_H
+
+#ifndef _KALCOMM_COMMON_H
+#include "common/common.h"
+#endif
+
+#ifndef _OSK_SOURCE
+#   define itoa _osk_itoa
+#   define atoi _osk_atoi
+#endif
+
+char *itoa(int, char *, int);
+
+#endif
diff --git a/src/kaleid/common/lib/convert.c b/src/kaleid/common/lib/convert.c
new file mode 100644
index 0000000..2731900
--- /dev/null
+++ b/src/kaleid/common/lib/convert.c
@@ -0,0 +1,52 @@
+//----------------------------------------------------------------------------//
+//                           GNU GPL OS/K                                     //
+//                                                                            //
+//  Authors:    spectral`                                                     //
+//              NeoX                                                          //
+//                                                                            //
+//  Desc:       Conversion utilities                                          //
+//----------------------------------------------------------------------------//
+
+#include "common/convert.h"
+
+//
+//  Digits table for bases <=36
+//
+static const char digits[36] =
+        "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+//
+//  Integer to string in any base between 2 and 36 (included)
+//
+char *itoa(int i, char *str, int base)
+{
+    int neg = 0;
+    char *orig = str;
+
+    if (base < 2 || base > 36)
+        return NULL;
+    
+    // deal with negatives
+    if (i < 0) {
+        neg = 1;
+        i = -i;
+    }
+    
+    // deal with zero separatly
+    if (i == 0) {
+        *str++ = '0';
+    }
+    
+    // compute digits... in reverse order (XXX?)
+    while (i > 0) {
+        *str++ = digits[i % base];
+        i /= base;
+    }
+
+    if (neg) *str++ = '-';
+    *str = '\0';
+
+    return reverse(orig);
+}
+
+
diff --git a/src/kaleid/common/lib/memory.c b/src/kaleid/common/lib/memory.c
new file mode 100644
index 0000000..3ebe6ee
--- /dev/null
+++ b/src/kaleid/common/lib/memory.c
@@ -0,0 +1,11 @@
+//----------------------------------------------------------------------------//
+//                           GNU GPL OS/K                                     //
+//                                                                            //
+//  Authors:    spectral`                                                     //
+//              NeoX                                                          //
+//                                                                            //
+//  Desc:       mem*() functions                                              //
+//----------------------------------------------------------------------------//
+
+#include "common/memory.h"
+
diff --git a/src/kaleid/common/lib/sprintf.c b/src/kaleid/common/lib/sprintf.c
new file mode 100644
index 0000000..1785a01
--- /dev/null
+++ b/src/kaleid/common/lib/sprintf.c
@@ -0,0 +1,75 @@
+//----------------------------------------------------------------------------//
+//                           GNU GPL OS/K                                     //
+//                                                                            //
+//  Authors:    spectral`                                                     //
+//              NeoX                                                          //
+//                                                                            //
+//  Desc:       sprintf()-related functions                                   //
+//----------------------------------------------------------------------------//
+
+#include "common/string.h"
+
+//
+//  Format str according to fmt using ellipsed arguments
+//
+int sprintf(char *str, const char *fmt, ...)
+{
+    int ret;
+    va_list ap;
+    
+    va_start(ap);
+    ret = vsnprintf(str, SIZE_T_MAX, fmt, ap);
+    va_end(ap);
+    
+    return ret;
+}
+
+//
+//  Format str according to fmt, using the va_list ap
+//
+int vsprintf(char *str, const char *fmt, va_list ap)
+{
+    return vsnprintf(str, SIZE_T_MAX, fmt, ap);
+}
+
+//
+//  sprintf() but with a size limit: no more than n bytes are written in str
+//  XXX null termination behavior?
+//
+int snprintf(char *str, size_t n, const char *fmt, ...)
+{
+    int ret;
+    va_list ap;
+    
+    va_start(ap);
+    ret = vsnprintf(str, n, fmt, ap)
+    va_end(ap);
+    
+    return ret;
+}
+
+//
+//  snprintf() but arguments
+//
+int vsnprintf(char *str, size_t n, const char *fmt, va_list ap)
+{
+    int ret = 0;
+    
+    while (*fmt && ret < n) {
+        if (*fmt != '%') {
+            *str++ = *fmt++;
+            ret++;
+            continue;
+        }
+        
+        switch (*fmt) {
+            case 'd':
+            default:
+            break;
+        }
+    }
+    
+    return ret;
+}
+
+
diff --git a/src/kaleid/common/lib/string.c b/src/kaleid/common/lib/string.c
index 083f269..f81f60c 100644
--- a/src/kaleid/common/lib/string.c
+++ b/src/kaleid/common/lib/string.c
@@ -11,15 +11,21 @@
 
 //  TODO multibyte, assembly
 
+//
+//  Returns str's length
+//
 size_t strlen(const char *str)
 {
     const char *base = str;
 
-    while (str) str++;
+    while (*str++);
 
-    return (str - base);
+    return (str - base - 1);
 }
 
+//
+//  Copy the string src into dest
+//
 char *strcpy(char *dest, const char *src)
 {
     char *base = dest;
@@ -27,6 +33,9 @@ char *strcpy(char *dest, const char *src)
     return base; 
 }
 
+//
+//  strcpy() but safer
+//
 char *strncpy(char *dest, const char *src, size_t n)
 {
     size_t i;
@@ -39,3 +48,20 @@ char *strncpy(char *dest, const char *src, size_t n)
     return dest;
 }
 
+//
+//  Reverses a string
+//
+char *reverse(char *str)
+{
+    char ch, *orig = str;
+    size_t n = strlen(str);
+    char *temp = str + n - 1;
+
+    while (temp > str) {
+        ch = *temp;
+        *temp-- = *str;
+        *str++ = ch;
+    }
+    
+    return orig;
+}
diff --git a/src/kaleid/common/memory.h b/src/kaleid/common/memory.h
new file mode 100644
index 0000000..a877e1a
--- /dev/null
+++ b/src/kaleid/common/memory.h
@@ -0,0 +1,18 @@
+//----------------------------------------------------------------------------//
+//                           GNU GPL OS/K                                     //
+//                                                                            //
+//  Authors:    spectral`                                                     //
+//              NeoX                                                          //
+//                                                                            //
+//  Desc:       mem*() functions                                              //
+//----------------------------------------------------------------------------//
+
+#ifndef _KALCOMM_MEMORY_H
+#define _KALCOMM_MEMORY_H
+
+#ifndef _KALCOMM_COMMON_H
+#include "common/common.h"
+#endif
+
+#endif
+
diff --git a/src/kaleid/common/status.h b/src/kaleid/common/status.h
index ee9516e..82387da 100644
--- a/src/kaleid/common/status.h
+++ b/src/kaleid/common/status.h
@@ -7,16 +7,23 @@
 //  Desc:       Values for status_t                                           //
 //----------------------------------------------------------------------------//
 
-
 #ifndef _KALCOMM_STATUS_H
 #define _KALCOMM_STATUS_H
 
-#define STATUS_FAILED(x)  ((x) < 0))
-#define STATUS_SUCCESS(x) (!STATUS_FAILED(x))
+#ifndef _KALCOMM_COMMON_H
+#error "don't include common/types.h without common/common.h"
+#endif
+
+#ifndef _OSK_SOURCE
+#   define describe_status _osk_describe_status
+#endif
 
 // see in common/lib/status.c for status messages
 const char *describe_status(status_t);
 
+#define STATUS_FAILED(x)  ((x) < 0))
+#define STATUS_SUCCESS(x) (!STATUS_FAILED(x))
+
 #define SUCCESS            (0)          // everything went fine
 
 #define FAILED             (-1)
diff --git a/src/kaleid/common/string.h b/src/kaleid/common/string.h
index bf5fdf3..0f8542d 100644
--- a/src/kaleid/common/string.h
+++ b/src/kaleid/common/string.h
@@ -11,11 +11,33 @@
 #ifndef _KALCOMM_STRING_H
 #define _KALCOMM_STRING_H
 
+#ifndef _KALCOMM_COMMON_H
 #include "common/common.h"
+#endif
+
+#ifndef _OSK_SOURCE
+
+#   define strlen _osk_strlen
+#   define strcpy _osk_strcpy
+#   define strncpy _osk_strncpy
+#   define reverse _osk_reverse
+
+#   define sprintf _osk_sprintf
+#   define snprintf _osk_snprintf
+#   define vsprintf _osk_vsprintf
+#   define vsnprintf _osk_vsnprintf
+
+#endif
 
 size_t strlen(const char *);
 char *strcpy(char *, const char *);
 char *strncpy(char *, const char *, size_t);
+char *reverse(char *);
+
+int sprintf(char *, const char *, ...);
+int snprintf(char *, size_t, const char *, ...);
+int vsprintf(char *, const char *, va_list);
+int vsnprintf(char *, size_t, const char *, va_list);
 
 #endif
 
diff --git a/src/kaleid/common/types.h b/src/kaleid/common/types.h
index abe48a5..fb7d4ff 100644
--- a/src/kaleid/common/types.h
+++ b/src/kaleid/common/types.h
@@ -11,21 +11,31 @@
 #ifndef _KALCOMM_TYPES_H
 #define _KALCOMM_TYPES_H
 
-typedef _Bool           bool;
-typedef unsigned char   uchar;
-typedef unsigned short  ushort;
-typedef unsigned int    uint;
-typedef unsigned long   ulong;
-typedef long double     ldouble;
-typedef short           status_t;
-typedef short           port_t;
-typedef uint            wchar_t;
-typedef ulong           size_t;
-typedef long            ssize_t;
-typedef size_t          off_t;
+#ifndef _KALCOMM_COMMON_H
+#error "don't include common/types.h without common/common.h"
+#endif
 
-typedef int             atomic_t;
-typedef ulong           pid_t;
+#ifndef KEEP_KALCOMM_TYPES_MINIMAL
+typedef _Bool               bool;
+typedef unsigned char       uchar;
+typedef unsigned short      ushort;
+typedef unsigned int        uint;
+typedef unsigned long       ulong;
+typedef long long           llong;
+typedef unsigned long long  ullong;
+typedef long double         ldouble;
+typedef uint                wchar_t;
+typedef ullong              size_t;
+typedef llong               ssize_t;
+typedef size_t              off_t;
+typedef int                 atomic_t;
+typedef ulong               pid_t;
+typedef void               *va_list;
+#endif
+
+typedef short               port_t;
+typedef short               status_t;
+// XXX limits
 
 #endif
 
diff --git a/src/kaleid/kernel/init.c b/src/kaleid/kernel/init.c
index 2ea9311..b6f268a 100644
--- a/src/kaleid/kernel/init.c
+++ b/src/kaleid/kernel/init.c
@@ -8,8 +8,12 @@
 //----------------------------------------------------------------------------//
 
 #include "kernel/init.h"
+#include "kernel/ke/panic.h"
 #include "kernel/io/terminal.h"
 
+//
+//  Entry point of kaleid-kernel.elf
+//
 void kstart(void)
 {    
     kterm_init();
diff --git a/src/kaleid/kernel/init.h b/src/kaleid/kernel/init.h
index 8238842..bb80788 100644
--- a/src/kaleid/kernel/init.h
+++ b/src/kaleid/kernel/init.h
@@ -11,8 +11,6 @@
 #define _KALKERN_INIT_H
 
 #include "common/common.h"
-#include "common/string.h"
-#include "kernel/ke/panic.h"
 
 // kernel entry point
 void kstart(void);
diff --git a/src/kaleid/linux/test-common.c b/src/kaleid/linux/test-common.c
new file mode 100644
index 0000000..a8c746e
--- /dev/null
+++ b/src/kaleid/linux/test-common.c
@@ -0,0 +1,45 @@
+//----------------------------------------------------------------------------//
+//                           GNU GPL OS/K                                     //
+//                                                                            //
+//  Authors:    spectral`                                                     //
+//              NeoX                                                          //
+//                                                                            //
+//  Desc:       Test file for common/                                         //
+//----------------------------------------------------------------------------//
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define KEEP_KALCOMM_TYPES_MINIMAL
+
+#include "common/common.h"
+#include "common/string.h"
+
+int main(int argc, char *argv[])
+{
+    (void)argc;
+    (void)argv;
+    
+    const char *test1 = "test string\n";
+    char *test2 = malloc(strlen(test1));
+    char *test3 = malloc(strlen(test1));
+
+    printf("1\n");
+
+    #undef strlen
+    assert(strlen("test string") == _osk_strlen("test string"));
+    
+    #undef strcpy
+    assert(strcmp(strcpy(test2, test1), _osk_strcpy(test3, test1)) == 0);
+    
+    
+    // tests done
+    printf("2\n");
+    
+    free(test2);
+    free(test3);
+    
+    return 0;
+}
+