HotSpot 5.0 Changes
-------------------
This release of HotSpot incorporates the following improvements:

1) New Feature #1: Heatsink and fan model
OPTIONAL: A parameterized heasink package model that lets users to 
explore the effect on cooling with different configurations of heatsink, 
fan and air fow. This feature is optinal. There are several newly added 
files: package.c, package.h and package.config. Commandline option 
'-package_model_used 1' activates this new feature. The option 
'-package_config_file <filename>' allows users to use their own package 
configuration file (format must comply to the example package.config). 

2) New Feature #2: Secondary heat transfer path
OPTIONAL: Package layers along the secondary heat tranfer path 
are included in this release (on-chip metal layers as a whole, C4 pads, 
package substrate, solder balls, and printed-circuit board). In most cases,
secondary heat transfer path can be neglected. However, in special cases 
such as oil flow over bare silicon die, the secondary heat transfer path
plays an important role and should be modeled (e.g. see our ISPASS'09
paper). To enable this feature, add '-model_secondary 1' in commandline
or in hotspot.config. Currently, the secondary heat tranfer path mode is
not supported if multiple silicon layers are configured.


3) New Feature #3: Leakage-temperature interactions
OPTIONAL: A simple leakage model interface that allows users to simulate
the temperature-leakage interaction. This feature can be enabled by adding
'-leakage_used 1' in commandline or hotspot.config. Users can use their own 
leakage model to replace what is inside calc_leakage() in temperature.c.
This feature is only supported in steady-state temperature calculations. 
Transient thermal-leakage loop is NOT supported, because the time scales of 
transient leakage power evolvement are not clear, and it is potentially 
wrong to assume instantaneous leakage update with increased temperature 
in each transient step ("sampling interval") in HotSpot.

4) Thermal properties of heasink, speader and thermal interface material are 
now configurable in 'hotspot.config', as opposed to being hard coded in
'temperature.h' in earlier releases.

5) Transient thermal time constant fitting factor is changed from 0.5 to 0.333,
for more accurate transient simulations. 0.5 was derived based on traditional
Elmore Delay model, which is not fully accurate for thermal RC circuit. Our
detailed analytical derivation reveals that a factor of 1/3 is the right factor
for lumped vs. distributed thermal RC circuits.

6) A sample hotspot.exe is included in companion with the MS Excel interface (
HotSpotUI-5.0.xls), for users who prefer not doing the Windows compilation. If this
.exe file doesn't work in your Windows system, follow instructions in HOWTO file
to compile HotSpot under Windows.
