AML

ACPI AML. More...

Collaboration diagram for AML:

Detailed Description

ACPI AML.

ACPI AML is a procedural turing complete bytecode language used to describe the hardware configuration of a computer system. A hardware manufacturer creates the bytecode to describe their hardware, and we, as the kernel, parse it. The bytecode contains instructions that create namespaces and provide device information, but it does not output this data, it's not like JSON or similar, instead AML itself expects a series of functions (e.g., for creating device objects, namespaces, etc.) that it can call to directly create these structures.

The parser works like a recursive descent parser. For example, according to the specification, the entire AML code block is defined as AMLCode := DefBlockHeader TermList, since we have already read the header, we then just call the aml_term_list_read() function. A termlist is defined as TermList := Nothing | <termobj termlist>, this is a recursive definition, which we could flatten to termobj termobj termobj ... Nothing. So we now call the aml_term_obj_read() function on each termobj. A termobj is defined as TermObj := Object | StatementOpcode | ExpressionOpcode we then determine if this TermObj is an Object, StatementOpcode, or ExpressionOpcode and continue down the chain until we finally have something to execute.

This parsing structure makes the parser a more or less 1:1 replica of the specification, hopefully making it easier to understand and maintain. But, it does also result in some overhead and redundant parsing, potentially hurting performance, however i believe the benefits outweigh the costs.

Throughout the documentation objects are frequently said to have a definition, a breakdown of how these definitions are read can be found in section 20.1 of the ACPI specification.

Modules
	Debugging
	Debugging.
	Args
	Arg Objecs Encoding.
	Data Objects
	Data Objects Encoding.
	Debug Objects
	Debug Objects Encoding.
	Expression Opcodes
	Expression Opcodes Encoding.
	Locals
	Local Objecs Encoding.
	Name Objects
	Name Objects Encoding.
	Namespace Modifier Objects
	Namespace Modifier Objects Encoding.
	Package Length
	Package Length Encoding.
	Statement Opcodes
	Statement Opcodes Encoding.
	Term Objects
	Term Objects Encoding.
	Integer
	Integer revision handling.
	Namespace
	Namespace and Namespace Overlays.
	Object
	Object.
	Patch-up
	Patch-up system for forward references.
	Predefined
	Predefined AML names and objects.
	Access Type
	Access Type Handling.
	Buffer Field
	Buffer Field.
	Compare
	Object Comparison.
	Concat
	Object Concatenation.
	Convert
	Data Type Conversion.
	Copy
	Copy.
	EISA ID
	EISA ID to string and vice versa conversion.
	Runtime Evaluation
	Object Runtime Evaluation.
	Field Access
	Opregion and Field Access.
	Methods
	Method Evaluation.
	Mid
	Extract Portion of Buffer or String.
	Mutex
	Mutex.
	Store
	Store.
	State
	State.
	String Conversion
	String Conversion.
	Tokens
	Tokens.

Macros
#define	AML_CURRENT_REVISION   0x20251010
	The current revision of the AML subsystem.

Functions
uint64_t	aml_init (void)
	Initialize the AML subsystem.
mutex_t *	aml_big_mutex_get (void)
	Get the mutex for the entire AML subsystem.

Macro Definition Documentation

AML_CURRENT_REVISION

#define AML_CURRENT_REVISION   0x20251010

The current revision of the AML subsystem.

This number as far as i can tell just needs to be larger than 2. But the ACPICA tests expect it to be greater or equal 0x20140114 and less then or equal 0x20500000. So we just use a date code. There is no need to update this.

Definition at line 46 of file aml.h.

Function Documentation

aml_init()

uint64_t aml_init

(

void

)

Initialize the AML subsystem.

Returns

On success, 0. On failure, ERR.

Definition at line 107 of file aml.c.

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aml_big_mutex_get()

mutex_t * aml_big_mutex_get

(

void

)

Get the mutex for the entire AML subsystem.

Must be held when interacting with any AML data structures.

Returns

mutex_t* A pointer to the mutex.

Definition at line 179 of file aml.c.

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