Specifications

12 IBM System z Personal Development Tool: Volume 3 Additional Topics
initrd ...
...
title Windows
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title Failsafe -- SUSE Linux
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Change the default number to 1 if you want to boot Windows by default. Change the timeout
value (which is in seconds) to a larger number if you want more time to make the selection
after booting the PC. Later Linux distributions have slightly changed the /boot partition and
the menu.lst file (or equivalent) may have moved.
1.11 Remote operation
A zPDT system (including z/OS) may be operated remotely, using a Linux command window
(telnet or VNC or ssh) and TN3270e sessions connected to the base Linux on the zPDT
system. No special techniques or setups are required. As with local operation, it is important
to have the TN3270e session for the z/OS console connected before IPLing z/OS.
Security considerations in your environment determine whether simple telnet or the more
secure ssh should be used for the Linux command windows used to control zPDT.
1.12 x3270 cursor position
The 3270 cursor in an x3270 cursor window may be positioned incorrectly if the window is
clicked to activate it. We used two methods to partly bypass this inconvenience when using
gnome 2:
򐂰 Click the top title bar of the x3270 window. This activates it (and
raises or redraws it, if
needed) without moving the 3270 cursor in the window.
򐂰 On slightly older SUSE releases, go to Computer  Control Center  Windows and
check the option “Select windows when the mouse moves over them.” This option is most
helpful when the x3270 window is not partly overlaid by another window.
򐂰 On slightly older Red Hat releases, go to System  Preferences  Windows and
check the option to select a window when the mouse moves over it.
Unfortunately, some current gnome 3 versions appear to have no way to control this action.
1.13 Devices, memory, msgmni, ulimit
The current version of zPDT has a maximum of 1024 emulated I/O devices. There is an
interaction between the actual number of I/O devices and the amount of memory available for
System z usage.
7
Each defined I/O device requires approximately 300 KB of shared virtual
memory in the Linux address spaces. In most cases, where the number of defined I/O
devices is small
8
, this is not a significant memory component. However, when the number of
emulated I/O devices grows into the hundreds, the amount of shared memory consumed
becomes significant.
7
This discussion is primarily for 32-bit Linux systems.
8
By “small” we mean numbers in the general range of 25 to 50 I/O devices. For example, a devmap with 40 devices
will cause about 10 MB of shared virtual memory to be used for I/O device support.