[Xen-devel] [PATCH]make "xm console" will not block VMX booting

["Yu, Ping Y" <ping.y.yu@xxxxxxxxx>]

There is a known "xm console" issue related with VMX. When "serial" is
enabled 
in script and no once uses "xm console" to read the console, VMX boting
will hang 
due to the buffer is full.
I added a "select" before "write". If it could not be written,
unix_write will 
Return immediately and it will not block the VMX booting. With this fix,
we can
 make VMX's serial enable by default.

Signed-off-by: Yu Ping <ping.y.yu@xxxxxxxxx>

diff -r 6ce7c026320e tools/examples/xmexample.vmx
--- a/tools/examples/xmexample.vmx      Mon Jan 16 23:54:24 2006
+++ b/tools/examples/xmexample.vmx      Wed Jan 18 16:23:10 2006
@@ -132,7 +132,7 @@
 
#-----------------------------------------------------------------------
------
 #   serial port re-direct to pty deivce, /dev/pts/n 
 #   then xm console or minicom can connect
-#serial='pty'
+serial='pty'
 
 
#-----------------------------------------------------------------------
-----
 # enable ne2000, default = 0(use pcnet)
diff -r 6ce7c026320e tools/ioemu/vl.c
--- a/tools/ioemu/vl.c  Mon Jan 16 23:54:24 2006
+++ b/tools/ioemu/vl.c  Wed Jan 18 16:23:10 2006
@@ -957,19 +957,34 @@
 
 static int unix_write(int fd, const uint8_t *buf, int len1)
 {
-    int ret, len;
+    int ret,sel_ret,len;
+    int max_fd;
+    fd_set writefds;
+    struct timeval timeout;
+
+    max_fd = fd;  
 
     len = len1;
     while (len > 0) {
-        ret = write(fd, buf, len);
-        if (ret < 0) {
-            if (errno != EINTR && errno != EAGAIN)
-                return -1;
-        } else if (ret == 0) {
-            break;
-        } else {
-            buf += ret;
-            len -= ret;
+        FD_ZERO(&writefds);
+        FD_SET(fd, &writefds);
+       timeout.tv_sec = 0;
+       timeout.tv_usec = 0;
+       sel_ret = select(max_fd + 1, NULL, &writefds, 0, &timeout);
+       if (sel_ret <= 0) {
+               /* Timeout or select error */
+            return -1;
+       } else {
+            ret = write(fd, buf, len);
+            if (ret < 0) {
+                if (errno != EINTR && errno != EAGAIN)
+                    return -1;
+            } else if (ret == 0) {
+                   break;
+            } else {
+                   buf += ret;
+                    len -= ret;
+            }
         }
     }
     return len1 - len;


Ping

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