Strange behaviour of X Driver

[Robert Lunnon]

I have some strange behaviour occurring on Solaris 10 I am getting XIO errors

I Did a syscal trace and got this in part \


 uname(0x7FD5EA54)                               = 1
uname(0x7FD5EB24)                               = 1
xstat(2, "/tmp/.X11-pipe/X0", 0x7FD5EF64)       = 0
open("/tmp/.X11-pipe/X0", O_RDWR)               = 11
ioctl(11, I_CANPUT, 0x00000000)                 = 1
uname(0x7FD5EA94)                               = 1
uname(0x7FD5EAC4)                               = 1
fcntl(11, F_SETFD, 0x00000001)                  = 0
access("/usr2/robert/.Xauthority", R_OK)        = 0
open("/usr2/robert/.Xauthority", O_RDONLY)      = 14
fstat64(14, 0x7FD5EC40)                         = 0
fstat64(14, 0x7FD5EB80)                         = 0
ioctl(14, TCGETA, 0x7FD5EC14)                   Err#25 ENOTTY
read(14, "\0\0\004C0A80305\001 0\0".., 8192)    = 1174
read(14, 0x080C413C, 8192)                      = 0
llseek(14, 0, SEEK_CUR)                         = 1174
close(14)                                       = 0
writev(11, 0x7FD5F6F4, 4)                       = 48
fcntl(11, F_GETFL)                              = 2
fcntl(11, F_SETFL, FWRITE|FNONBLOCK)            = 0
read(11, 0x7FD5F7AC, 8)                         Err#11 EAGAIN
XIO:  fatal IO error write(2, " X I O :     f a t a l  ".., 21) = 21
0 (write(2, " 0   (", 3)                                = 3
Error 0write(2, " E r r o r   0", 7)                    = 7
) on X server "write(2, " )   o n   X   s e r v e".., 15)       = 15
:0.0write(2, " : 0 . 0", 4)                             = 4
"
write(2, " "\r\n", 3)                           = 3
      after write(2, "             a f t e r  ", 12)    = 12
0write(2, " 0", 1)                              = 1
 requests (write(2, "   r e q u e s t s   (", 11)               = 11
0write(2, " 0", 1)                              = 1
 known processed) with write(2, "   k n o w n   p r o c e".., 23)       = 23
0write(2, " 0", 1)                              = 1
 events remaining.
write(2, "   e v e n t s   r e m a".., 20)      = 20
_exit(1)

The last X IO operation before the  fatal error was called was  a read n the X 
pipe which return error EAGAIN

The Man page for read(2) says the following

   When attempting to read from an empty pipe (or FIFO):

        o  If no process has the pipe open  for  writing,  read()
           returns 0 to indicate end-of-file.

        o  If some process has the  pipe  open  for  writing  and
           O_NDELAY is set, read() returns 0.

        o  If some process has the  pipe  open  for  writing  and
           O_NONBLOCK is set, read() returns -1 and sets errno to
           EAGAIN.


So, Its quite possible, likely that the  X Server has the pipe open for 
writing but  the pipe is empty which would return EAGAIN, why is this then 
treated as an error ???

More later....
Bob