diff --git a/configure.ac b/configure.ac
index f94b88c..03beb36 100644
--- a/configure.ac
+++ b/configure.ac
@@ -515,9 +515,9 @@ AC_MSG_RESULT([$FONTPATH])
 AC_ARG_WITH(xkb-path,         AS_HELP_STRING([--with-xkb-path=PATH], [Path to XKB base dir (default: ${datadir}/X11/xkb)]),
 				[ XKBPATH="$withval" ],
 				[ XKBPATH="${datadir}/X11/xkb" ])
-AC_ARG_WITH(xkb-output,       AS_HELP_STRING([--with-xkb-output=PATH], [Path to XKB output dir (default: ${datadir}/X11/xkb/compiled)]),
+AC_ARG_WITH(xkb-output,       AS_HELP_STRING([--with-xkb-output=PATH], [Path to XKB output dir (default: ${localstatedir}/cache/xkb)]),
 				[ XKBOUTPUT="$withval" ],
-				[ XKBOUTPUT="compiled" ])
+				[ XKBOUTPUT="${localstatedir}/cache/xkb" ])
 AC_ARG_WITH(default-xkb-rules, AS_HELP_STRING([--with-default-xkb-rules=RULES],
                                    [Keyboard ruleset (default: base/evdev)]),
                                 [ XKB_DFLT_RULES="$withval" ],
@@ -1202,7 +1202,7 @@ AC_DEFINE_DIR(XKB_BIN_DIRECTORY, XKB_BIN_DIRECTORY, [Path to XKB bin dir])
 dnl Make sure XKM_OUTPUT_DIR is an absolute path
 XKBOUTPUT_FIRSTCHAR=`echo $XKBOUTPUT | cut -b 1`
 if [[ x$XKBOUTPUT_FIRSTCHAR != x/ -a x$XKBOUTPUT_FIRSTCHAR != 'x$' ]] ; then
-   XKBOUTPUT="$XKB_BASE_DIRECTORY/$XKBOUTPUT"
+   AC_MSG_ERROR([xkb-output must be an absolute path.])
 fi
 
 dnl XKM_OUTPUT_DIR (used in code) must end in / or file names get hosed
diff --git a/xkb/README.compiled b/xkb/README.compiled
index 71caa2f..a4a2ae0 100644
--- a/xkb/README.compiled
+++ b/xkb/README.compiled
@@ -4,10 +4,10 @@ current keymap and/or any scratch keymaps used by clients.  The X server
 or some other tool might destroy or replace the files in this directory,
 so it is not a safe place to store compiled keymaps for long periods of
 time.  The default keymap for any server is usually stored in:
-     X<num>-default.xkm
-where <num> is the display number of the server in question, which makes
-it possible for several servers *on the same host* to share the same 
-directory.
+     server-<SHA1>.xkm
+
+where <SHA1> is the SHA1 hash of keymap source, so that compiled
+keymap of different keymap sources are stored in different files.
 
 Unless the X server is modified, sharing this directory between servers on
 different hosts could cause problems.
diff --git a/xkb/ddxLoad.c b/xkb/ddxLoad.c
index 1961423..411b677 100644
--- a/xkb/ddxLoad.c
+++ b/xkb/ddxLoad.c
@@ -30,6 +30,12 @@ THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
 #include <xkb-config.h>
 
+#ifdef HAVE_SHA1_IN_LIBMD /* Use libmd for SHA1 */
+# include <sha1.h>
+#else /* Use OpenSSL's libcrypto */
+# include <stddef.h>  /* buggy openssl/sha.h wants size_t */
+# include <openssl/sha.h>
+#endif
 #include <stdio.h>
 #include <ctype.h>
 #include <X11/X.h>
@@ -43,20 +49,9 @@ THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #define	XKBSRV_NEED_FILE_FUNCS
 #include <xkbsrv.h>
 #include <X11/extensions/XI.h>
+#include <errno.h>
 #include "xkb.h"
 
-        /*
-         * If XKM_OUTPUT_DIR specifies a path without a leading slash, it is
-         * relative to the top-level XKB configuration directory.
-         * Making the server write to a subdirectory of that directory
-         * requires some work in the general case (install procedure
-         * has to create links to /var or somesuch on many machines),
-         * so we just compile into /usr/tmp for now.
-         */
-#ifndef XKM_OUTPUT_DIR
-#define	XKM_OUTPUT_DIR	"compiled/"
-#endif
-
 #define	PRE_ERROR_MSG "\"The XKEYBOARD keymap compiler (xkbcomp) reports:\""
 #define	ERROR_PREFIX	"\"> \""
 #define	POST_ERROR_MSG1 "\"Errors from xkbcomp are not fatal to the X server\""
@@ -166,13 +161,56 @@ OutputDirectory(char *outdir, size_t size)
 }
 
 static Bool
+Sha1Asc(char sha1Asc[SHA_DIGEST_LENGTH*2+1], const char * input)
+{
+    int i;
+    unsigned char sha1[SHA_DIGEST_LENGTH];
+
+#ifdef HAVE_SHA1_IN_LIBMD /* Use libmd for SHA1 */
+    SHA1_CTX ctx;
+
+    SHA1Init (&ctx);
+    SHA1Update (&ctx, input, strlen(input));
+    SHA1Final (sha1, &ctx);
+#else /* Use OpenSSL's libcrypto */
+    SHA_CTX ctx;
+    int success;
+
+    success = SHA1_Init (&ctx);
+    if (! success)
+	return BadAlloc;
+
+    success = SHA1_Update (&ctx, input, strlen(input));
+    if (! success)
+	return BadAlloc;
+
+    success = SHA1_Final (sha1, &ctx);
+    if (! success)
+	return BadAlloc;
+#endif
+
+    /* convert sha1 to sha1_asc */
+    for(i=0; i<SHA_DIGEST_LENGTH; ++i) {
+	sprintf(sha1Asc+i*2, "%02X", sha1[i]);
+    }
+
+    return Success;
+}
+
+/* call xkbcomp and compile XKB keymap, return xkm file name in
+   nameRtrn */
+static Bool
 XkbDDXCompileKeymapByNames(XkbDescPtr xkb,
                            XkbComponentNamesPtr names,
                            unsigned want,
                            unsigned need, char *nameRtrn, int nameRtrnLen)
 {
     FILE *out;
-    char *buf = NULL, keymap[PATH_MAX], xkm_output_dir[PATH_MAX];
+    char *buf = NULL, xkmfile[PATH_MAX], xkm_output_dir[PATH_MAX];
+    char *tmpXkmFile = NULL;
+    char *canonicalXkmFileName = NULL;
+    char sha1Asc[SHA_DIGEST_LENGTH*2+1], xkbKeyMapBuf[100*1024];
+    int ret, result;
 
     const char *emptystring = "";
     char *xkbbasedirflag = NULL;
@@ -183,15 +221,67 @@ XkbDDXCompileKeymapByNames(XkbDescPtr xkb,
     /* WIN32 has no popen. The input must be stored in a file which is
        used as input for xkbcomp. xkbcomp does not read from stdin. */
     char tmpname[PATH_MAX];
-    const char *xkmfile = tmpname;
+    const char *xkbfile = tmpname;
 #else
-    const char *xkmfile = "-";
+    const char *xkbfile = "-";
+#endif
+
+    /* Write keymap source (xkbfile) to memory buffer `xkbKeyMapBuf',
+       of which SHA1 is generated and used as result xkm file name  */
+    memset(xkbKeyMapBuf, 0, sizeof(xkbKeyMapBuf));
+    out = fmemopen(xkbKeyMapBuf, sizeof(xkbKeyMapBuf), "w");
+    if (NULL == out) {
+        ErrorF("[xkb] Open xkbKeyMapBuf for writing failed\n");
+        return FALSE;
+    }
+    ret = XkbWriteXKBKeymapForNames(out, names, xkb, want, need);
+    if (fclose(out) !=0) {
+        ErrorF("[xkb] XkbWriteXKBKeymapForNames error, perhaps xkbKeyMapBuf is too small\n");
+        return FALSE;
+    }
+#ifdef DEBUG
+    if (xkbDebugFlags) {
+        ErrorF("[xkb] XkbDDXCompileKeymapByNames compiling keymap:\n");
+        fputs(xkbKeyMapBuf, stderr);
+    }
 #endif
+    if (!ret) {
+        ErrorF("[xkb] Generating XKB Keymap failed, giving up compiling keymap\n");
+        return FALSE;
+    }
 
-    snprintf(keymap, sizeof(keymap), "server-%s", display);
+    DebugF("[xkb] computing SHA1 of keymap\n");
+    if (Success == Sha1Asc(sha1Asc, xkbKeyMapBuf)) {
+        snprintf(xkmfile, sizeof(xkmfile), "server-%s", sha1Asc);
+    } else {
+        ErrorF("[xkb] Computing SHA1 of keymap failed, "
+               "using display name instead as xkm file name\n");
+        snprintf(xkmfile, sizeof(xkmfile), "server-%s", display);
+    }
 
     OutputDirectory(xkm_output_dir, sizeof(xkm_output_dir));
 
+    /* set nameRtrn, fail if it's too small */
+    if ((strlen(xkmfile)+1 > nameRtrnLen) && nameRtrn) {
+        ErrorF("[xkb] nameRtrn too small to hold xkmfile name\n");
+        return FALSE;
+    }
+    strncpy(nameRtrn, xkmfile, nameRtrnLen);
+
+    /* if the xkm file already exists, reuse it */
+    canonicalXkmFileName = Xprintf("%s%s.xkm", xkm_output_dir, xkmfile);
+    if (access(canonicalXkmFileName, R_OK) == 0) {
+        /* yes, we can reuse the old xkm file */
+        LogMessage(X_INFO, "XKB: reuse xkmfile %s\n", canonicalXkmFileName);
+        result = TRUE;
+        goto _ret;
+    }
+    LogMessage(X_INFO, "XKB: generating xkmfile %s\n", canonicalXkmFileName);
+
+    /* continue to call xkbcomp to compile the keymap. to avoid race
+       condition, we compile it to a tmpfile then rename it to
+       xkmfile */
+
 #ifdef WIN32
     strcpy(tmpname, Win32TempDir());
     strcat(tmpname, "\\xkb_XXXXXX");
@@ -214,15 +304,21 @@ XkbDDXCompileKeymapByNames(XkbDescPtr xkb,
         }
     }
 
+    if ( (tmpXkmFile = tempnam(xkm_output_dir, NULL)) == NULL ) {
+        ErrorF("[xkb] Can't generate temp xkm file name");
+        result = FALSE;
+        goto _ret;
+    }
+
     if (asprintf(&buf,
                  "\"%s%sxkbcomp\" -w %d %s -xkm \"%s\" "
-                 "-em1 %s -emp %s -eml %s \"%s%s.xkm\"",
+                 "-em1 %s -emp %s -eml %s \"%s\"",
                  xkbbindir, xkbbindirsep,
                  ((xkbDebugFlags < 2) ? 1 :
                   ((xkbDebugFlags > 10) ? 10 : (int) xkbDebugFlags)),
-                 xkbbasedirflag ? xkbbasedirflag : "", xkmfile,
+                 xkbbasedirflag ? xkbbasedirflag : "", xkbfile,
                  PRE_ERROR_MSG, ERROR_PREFIX, POST_ERROR_MSG1,
-                 xkm_output_dir, keymap) == -1)
+                 tmpXkmFile) == -1)
         buf = NULL;
 
     free(xkbbasedirflag);
@@ -233,6 +329,11 @@ XkbDDXCompileKeymapByNames(XkbDescPtr xkb,
         return FALSE;
     }
 
+    /* there's a potential race condition between calling tempnam()
+       and invoking xkbcomp to write the result file (potential temp
+       file name conflicts), but since xkbcomp is a standalone
+       program, we have to live with this */
+
 #ifndef WIN32
     out = Popen(buf, "w");
 #else
@@ -240,32 +341,41 @@ XkbDDXCompileKeymapByNames(XkbDescPtr xkb,
 #endif
 
     if (out != NULL) {
-#ifdef DEBUG
-        if (xkbDebugFlags) {
-            ErrorF("[xkb] XkbDDXCompileKeymapByNames compiling keymap:\n");
-            XkbWriteXKBKeymapForNames(stderr, names, xkb, want, need);
+        /* write XKBKeyMapBuf to xkbcomp */
+        if (EOF==fputs(xkbKeyMapBuf, out))
+        {
+            ErrorF("[xkb] Sending keymap to xkbcomp failed\n");
+            result = FALSE;
+            goto _ret;
         }
-#endif
-        XkbWriteXKBKeymapForNames(out, names, xkb, want, need);
 #ifndef WIN32
         if (Pclose(out) == 0)
 #else
         if (fclose(out) == 0 && System(buf) >= 0)
 #endif
         {
+            /* xkbcomp success */
             if (xkbDebugFlags)
                 DebugF("[xkb] xkb executes: %s\n", buf);
-            if (nameRtrn) {
-                strlcpy(nameRtrn, keymap, nameRtrnLen);
+            /* if canonicalXkmFileName already exists now, we simply
+               overwrite it, this is OK */
+            ret = rename(tmpXkmFile, canonicalXkmFileName);
+            if (0 != ret) {
+                ErrorF("[xkb] Can't rename %s to %s, error: %s\n",
+                       tmpXkmFile, canonicalXkmFileName,
+                       strerror(errno));
+
+                /* in case of error, don't unlink tmpXkmFile, leave it
+                   for debugging */
+
+                result = FALSE;
+                goto _ret;
             }
-            free(buf);
-#ifdef WIN32
-            unlink(tmpname);
-#endif
-            return TRUE;
+            result = TRUE;
+            goto _ret;
         }
         else
-            LogMessage(X_ERROR, "Error compiling keymap (%s)\n", keymap);
+            LogMessage(X_ERROR, "Error compiling keymap (%s)\n", xkbfile);
 #ifdef WIN32
         /* remove the temporary file */
         unlink(tmpname);
@@ -280,8 +390,15 @@ XkbDDXCompileKeymapByNames(XkbDescPtr xkb,
     }
     if (nameRtrn)
         nameRtrn[0] = '\0';
+    result = FALSE;
+
+_ret:
+    if (tmpXkmFile)
+        free(tmpXkmFile);
+    if (canonicalXkmFileName)
+        xfree(canonicalXkmFileName);
     free(buf);
-    return FALSE;
+    return result;
 }
 
 static FILE *
@@ -368,7 +485,6 @@ XkbDDXLoadKeymapByNames(DeviceIntPtr keybd,
                (*xkbRtrn)->defined);
     }
     fclose(file);
-    (void) unlink(fileName);
     return (need | want) & (~missing);
 }
 
-- 
1.7.7.3