Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3, Manual

Page: 694 / 1898

2:446 Volume 2, Part 1: Processor Abstraction Layer
PAL_PROC_GET_FEATURES
PAL_PROC_GET_FEATURES – Get Processor Dependent Features
(17)
Purpose:
Provides information about configurable processor features.
Calling Conv:
Static Registers Only
Mode:
Physical
Buffer:
Not dependent
Arguments:
Returns:
Status:
Description:
PAL_PROC_GET_FEATURES and PAL_PROC_SET_FEATURES procedure calls are used
together to describe current settings of processor features and to allow modification of
some of these processor features.
The feature_set input argument for PAL_PROC_GET_FEATURES describes which
processor feature_set information is being requested. Table 11-112 describes processor
feature_set zero. The feature_set values are split into two categories: architected and
implementation-specific. The architected feature sets have values from 0-15. The
implementation-specific feature sets are values 16 and above. The architected feature
sets are described in this document. The implementation-specific feature sets are
described in processor-specific documentation.
This procedure will return an invalid argument if an unsupported architectural
feature_set is passed as an input. Implementation-specific feature sets will start at 16
and will expand in an ascending order as new implementation-specific feature sets are
added. The return
status is used by the caller to know which implementation-specific
feature sets are currently supported on a particular processor.
For each valid feature_set , this procedure returns which processor features are
implemented in the features_avail return argument, the current feature setting is in
feature_status return argument, and the feature controllability in the feature_control
return argument. Only the processor features which are implemented and controllable
can be changed via PAL_PROC_SET_FEATURES. Features for which features_avail are 0
(unimplemented features) also have features_status and features_control of 0.
In Table 11-112 , the class field indicates whether a feature is required to be available
( Req. ) or is optional ( Opt. ). The control field indicates which features are required to be
controllable. Req. indicates that the feature must be controllable, Opt. indicates that
Argument Description
index Index of PAL_PROC_GET_FEATURES within the list of PAL procedures.
Reserved 0
feature_set Feature set information is being requested for.
Reserved 0
Return Value Description
status Return status of the PAL_PROC_GET_FEATURES procedure.
features_avail 64-bit vector of features implemented. See Table 11-112 .
feature_status 64-bit vector of current feature settings. See Table 11-112 .
feature_control 64-bit vector of features controllable by software.
Status Value Description
1 Call completed without error; The feature_set passed is not supported but a feature_set of a
larger value is supported
0 Call completed without error
-2 Invalid argument
-3 Call completed with error
-8 feature_set passed is beyond the maximum feature_set supported