Patch Name:  PHKL_3790

Patch Description: s700 9.01 Interrupting GCDESCRIBE ioctl can panic sti_save

    The frame-buffer driver, part of the graphics display driver set,
    allows users to obtain information about the display through the
    GCDESCRIBE ioctl call.  Since the frame-buffer can be in use by the
    Internal Terminal Emulator (ITE), the frame-buffer driver and ITE
    implement a semaphoring scheme to ensure the two can both safely
    access the graphics hardware without interacting.

    Unfortunately, it is possible for the GCDESCRIBE ioctl to exit
    prematurely, after it has grabbed the semaphore; this leaves the
    hardware locked, so that the ITE cannot gain access.  After some
    time, the ITE times out waiting on the semaphore and panics, with
    the message "sti_save(): timeout on semaphore."

    Specifically, the GCDESCRIBE ioctl locks the semaphore, then tries
    to save the graphics display state; since it is possible for the
    display to be busy, the driver enters a retry loop, calling sleep()
    with a short (.04 second) timeout.  The problem is that the sleep()
    is made at an interruptible priority (> PZERO), so that user signals
    cause the ioctl to return immediately; while this is appropriate
    design, since it avoids process delays, the sleep() does not take
    into account the semaphore lock.  Thus, when any user signal
    interrupts the process, the sleep() performs a longjmp, returning
    directly to the user program -- leaving the semaphore locked.

    The fix was to modify the sleep() call to catch the signal, by
    setting PCATCH; in this way, the ioctl can release the semaphore
    before returning to the user.

    An equivalent patch for HP-UX Release 9.03 is PHKL_3791.

Path Name:  /hp-ux_patches/s700/9.X/PHKL_3790

Effective Date:  940214

OS Release:  9.01

Reboot Required:  Yes

Patch Files:  /etc/conf/libhp-ux.a(framebuf.o)

SR#:  5003179754

"what" string/timestamp:  
    framebuf.c    $Revision: 1.15.81.3 $ $Date: 94/02/14 15:51:56 $ PATCH_9.01
 (PHKL_3790)

"sum" output:  53909 28 framebuf.o

Dependencies:  None

Supersedes:  None

H/W Dependencies:  None

Special Installation Instructions:  None.

Patch Installation Recommendation: Recommended for all systems, in particular
        those with customer-written programs that access the graphics
        display, and may perform GCDESCRIBE ioctls.

Patch Package Size:  72 Kbytes

Installation Instructions:  

     Please review all instructions and the Hewlett-Packard
     SupportLine User Guide or your Hewlett-Packard support terms
     and conditions for precautions, scope of license,
     restrictions, and, limitation of liability and warranties,
     before installing this patch.

     Note: Please back up your system before you patch.

---------------------------------------------------------------------------
After getting the patch onto your machine, unshar the patch (sh PHKL_3790).

To install this patch do the following:
1) Run /etc/update (Note: you must be logged in as root to update
   a system).
2) Once in the update "Main Menu" move the highlighted line to "Change
   Source or Destination ->" and press "Return" or "Select Item".
3) Make sure the highlighted item in the "Change Source or Destination"
   window is "From Tape Device to Local System ...", then press "Return" or
   "Select Item".
4) You should now be in the "From Tape Device to Local System" window.
   Change the "Source:  /dev/rmt/0m" to "Source: /tmp/PHKL_3790.updt"
   (this assumes that you are in the /tmp directory where PHKL_3790.updt
   has been placed).  Note: You must enter the complete path name.
5) Press "Done".
6) From here on follow the standard directions for update.

The customized script that update runs will move the original software
to /system/PHKL_3790/orig.  HP recommends keeping this software there in
order to recover from any potential problems.  It is also recommended that
you move the PHKL_3790.text file to /system/PHKL_3790 to be retained for
future reference.

If you wish to put this patch on a magnetic tape and update from the tape
drive, dd a copy of the patch to the tape drive.  As an example the
following will create a copy of the patch that update can read:
dd if=PHKL_3790.updt of=/dev/rmt/0m bs=2048