diff -r 6ed4368b4a9e xen/common/sysctl.c
--- a/xen/common/sysctl.c	Sun Oct 15 09:53:20 2006 +0100
+++ b/xen/common/sysctl.c	Wed Oct 11 11:37:27 2006 +0900
@@ -50,7 +50,8 @@ long do_sysctl(XEN_GUEST_HANDLE(xen_sysc
         ret = read_console_ring(
             guest_handle_cast(op->u.readconsole.buffer, char),
             &op->u.readconsole.count,
-            op->u.readconsole.clear);
+            op->u.readconsole.clear,
+            &op->u.readconsole.cindex);
         if ( copy_to_guest(u_sysctl, op, 1) )
             ret = -EFAULT;
     }
diff -r 6ed4368b4a9e xen/drivers/char/console.c
--- a/xen/drivers/char/console.c	Sun Oct 15 09:53:20 2006 +0100
+++ b/xen/drivers/char/console.c	Wed Oct 11 11:37:27 2006 +0900
@@ -66,13 +66,16 @@ static void putchar_console_ring(int c)
         conringc = conringp - CONRING_SIZE;
 }
 
-long read_console_ring(XEN_GUEST_HANDLE(char) str, u32 *pcount, int clear)
+long read_console_ring(XEN_GUEST_HANDLE(char) str, u32 *pcount, int clear, u32 *pcindex)
 {
     unsigned int idx, len, max, sofar, c;
     unsigned long flags;
 
     max   = *pcount;
     sofar = 0;
+
+    if ( clear < 0 )
+        goto readbyindex;
 
     c = conringc;
     while ( (c != conringp) && (sofar < max) )
@@ -100,6 +103,36 @@ long read_console_ring(XEN_GUEST_HANDLE(
     }
 
     *pcount = sofar;
+    return 0;
+
+readbyindex:
+    c = *pcindex;
+    if ( conringp < c )
+    {
+        *pcindex = conringp - CONRING_SIZE;
+        *pcount = sofar;
+        return 0;
+    }
+
+    if (((conringp - c) > CONRING_SIZE) || (conringp < c))
+        c = conringp - CONRING_SIZE;
+
+    while ( (c != conringp) && (sofar < max) )
+    {
+        idx = CONRING_IDX_MASK(c);
+        len = conringp - c;
+        if ( (idx + len) > CONRING_SIZE )
+            len = CONRING_SIZE - idx;
+        if ( (sofar + len) > max )
+            len = max - sofar;
+        if ( copy_to_guest_offset(str, sofar, &conring[idx], len) )
+            return -EFAULT;
+        sofar += len;
+        c += len;
+    }
+
+    *pcindex = c;
+    *pcount  = sofar;
     return 0;
 }
 
diff -r 6ed4368b4a9e xen/include/public/sysctl.h
--- a/xen/include/public/sysctl.h	Sun Oct 15 09:53:20 2006 +0100
+++ b/xen/include/public/sysctl.h	Fri Oct 20 21:35:15 2006 +0900
@@ -24,10 +24,12 @@
 #define XEN_SYSCTL_readconsole       1
 struct xen_sysctl_readconsole {
     /* IN variables. */
-    uint32_t clear;                /* Non-zero -> clear after reading. */
+    int32_t clear;                /* Greater-than-zero -> clear after reading. */
+                                  /* Less-than-zero -> use caller index. */
     XEN_GUEST_HANDLE(char) buffer; /* Buffer start */
     /* IN/OUT variables. */
     uint32_t count;            /* In: Buffer size;  Out: Used buffer size  */
+    uint32_t cindex;           /* In: Consumer index; Out: Next index */
 };
 typedef struct xen_sysctl_readconsole xen_sysctl_readconsole_t;
 DEFINE_XEN_GUEST_HANDLE(xen_sysctl_readconsole_t);
diff -r 6ed4368b4a9e xen/include/xen/console.h
--- a/xen/include/xen/console.h	Sun Oct 15 09:53:20 2006 +0100
+++ b/xen/include/xen/console.h	Wed Oct 11 11:37:27 2006 +0900
@@ -13,7 +13,7 @@
 
 void set_printk_prefix(const char *prefix);
 
-long read_console_ring(XEN_GUEST_HANDLE(char), u32 *, int);
+long read_console_ring(XEN_GUEST_HANDLE(char), u32 *, int, u32 *);
 
 void init_console(void);
 void console_endboot(void);