View source for ENH SUSPEND

{{DISPLAYTITLE:ENH_SUSPEND}}
Related to the software support package for Intel's SpeedStep dynamic frequency scaling technology (codenamed ''Geyserville'') '''Enhanced Suspend''' support is designed to allow the system to refresh the display once the system is resumed from a D3 Cold suspend state.

The Enhanced Suspend option should be enabled on a system with D3 Cold suspend enabled, if there is insufficient, disabled, or no BIOS assistence for restoring the video state once the system is resumed. On other systems, or in other circumstances, Enhanced Suspend may also be optionally enabled, if desired.

To control the Enhanced Suspend feature, the following statement should be used in the CONFIG.SYS file:
 SET ENH_SUSPEND=<value>

==Parameters==
where <value> is one of the following:
;0:the Enhanced Suspend is disabled, same as no "SET ENH_SUSPEND" statement in the CONFIG.SYS;
;1:basic Enhanced Suspend is enabled;
;2:same as "1" plus saving/restoration of the graphics mode screen.

SET ENH_SUSPEND=1 should be satisfactory in most cases, and requires the minimum of additional memory at the time of a suspend. However, there are circumstances such as a lockup desktop, or a PM Popup, where relatively unimportant video display content remains temporarily corrupted until the lockup or Popup is ended.

SET ENH_SUSPEND=2 requires additional memory to save and restore the exact the desktop bit pattern fairly immediately. It may yield results similar to SET ENH_SUSPEND=1 if system memory or virtual address space is in short supply at the time of the suspend.

'''NOTE:''' Suspend and resume may take longer when Enhanced Suspend is enabled. During suspend, some systems will produce a text screen advising the user that the system is suspending. Likewise, upon resume, a similar message may be displayed. Drivers are readied before the video is restored. On some systems, resume feels almost instantaneous, because by the time video is available, all other hardware has been awakened and the system is ready for input.

There are some system states for which the Enhanced Suspend support requires a newer version of display driver to avoid display corruption upon resume from a D3 Cold suspend state. It is recommended that the video driver claims support for Enhanced Suspend. The latest SciTech SNAP, IBMGRADD, and VGA/SVGA drivers have support for Enhanced Suspend. This would include Panorama, as well.

[[Category:Environment variable]]