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smapi (4)
>> smapi (4) ( FreeBSD man: Специальные файлы /dev/* )
BSD mandoc
NAME
smapi
- System Management Application Program Interface driver
DESCRIPTION
Many
IBM Thinkpad
laptops utilize a special software interface known as
SMAPI
(System Management Application Program Interface).
This interface controls various aspects of the system including:
System Interface
(the
BIOS
can store system information such as the system identifier),
System Configuration (where devices such as the display can be configured),
Power Management (software can interact with the
SMAPI BIOS
for Power Management control).
Client software must locate a
``header image''
stored in the
F000
segment in the
Thinkpad ROM
(read-only memory), which resides at the 16-byte boundary.
This is considered the
``Entry Point''
for the service.
The
``header image''
stores information like:
signature,
SMAPI
version (major and minor),
header image length,
checksum information (which verifies the image),
an Information Word (used to identify the
BIOS
service level),
Real Mode Entry Point (where clients using the
Real/V86 mode for the far-call value),
and finally a 16-bit/32-bit Protected Mode Entry
Point: base code address which specifies the
BIOS
physical address.
The client must prepare a 64 kilobyte selector for this
BIOS )
To invoke the
SMAPI BIOS
a far-call must be used on the entry point specified in the header file.
All other information should be stored in the client data area.
The client is required to prepare both an input and output parameter in a
data area of its own.
This area can be
``informed''
by pushing those pointers into its stack before the far-calls.
The
SMAPI BIOS
uses the stack and data areas with the selector during a
BIOS
invocation, thus the caller must define the same privilege area as the
BIOS
The parameter structure will be made up by using the input and output
fields prepared by the caller.
The input field will specify the function request to the
BIOS
The
BIOS
will then drop a return value into the output field.
These fields are made up of three parts.
The first holds parameters, function numbers, and return codes.
The next will contain an offset in hexadecimal.
Finally a length field which is comprised of Byte, Word, or Double Word.
