#9635 LOW 1.5-sof: chvt hangs after telinit 1 followed by telinit 5

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#9635: chvt hangs after telinit 1 followed by telinit 5
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           Reporter:  Quozl     |       Owner:  dsaxena                          
               Type:  defect    |      Status:  new                              
           Priority:  low       |   Milestone:  1.5-software-update              
          Component:  kernel    |     Version:  Development build as of this date
         Resolution:            |    Keywords:  os34 os36 os52 chvt              
        Next_action:  diagnose  |    Verified:  0                                
Deployment_affected:            |   Blockedby:                                   
           Blocking:            |  
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Comment(by Quozl):

 In the failed state X consumes 100% CPU, and strace of X shows a loop
 failing ioctl on /dev/tty3:

 {{{
 ioctl(7, TCFLSH, 0x2)                   = -1 EIO (Input/output error)
 setitimer(ITIMER_REAL, {it_interval={0, 20000}, it_value={0, 20000}},
 NULL) = 0
 clock_gettime(CLOCK_MONOTONIC, {5983, 66583297}) = 0
 clock_gettime(CLOCK_MONOTONIC, {5983, 66644618}) = 0
 setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 0}}, NULL) = 0
 clock_gettime(CLOCK_MONOTONIC, {5983, 66777386}) = 0
 select(256, [1 3 4 5 7 10 15 16 17 18 19 20 21 22], NULL, NULL, {7,
 393000}) = 1 (in [7], left {7, 392990})
 clock_gettime(CLOCK_MONOTONIC, {5983, 67001157}) = 0
 ioctl(7, TCFLSH, 0x2)                   = -1 EIO (Input/output error)

 }}}

 Killing the X server causes another to be started, and during that startup
 the laptop hangs hard; no response to serial port, keyboard, touchpad,
 power button, or lid close switch.

 Reproduced on three laptops.

 With serial port connected the following output is visible at time of X
 server restart:

 {{{
 [root at xo-73-22-5d dev]# ps ax|grep X
 3076 ?        Rs     1:11 X :0 -wr -auth /var/tmp/olpc-auth/.Xserverauth
 3324 ttyS0    S+     0:00 grep X
 [root at xo-73-22-5d dev]# kill 3076
 [root at xo-73-22-5d dev]# [  247.592231] dcon_freeze_store: 0
 [  254.431770] dcon_freeze_store: 0
 }}}

 The image on screen appears to be a partially completed full screen paint
 with a black VT cursor block top left corner.

 I suspect a graphics driver.

-- 
Ticket URL: <http://dev.laptop.org/ticket/9635#comment:6>
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