本文主要浅谈自己对ACPI DSDT table的理解。

Differentiated System Description Table (DSDT) for system configuration info. DSDT is a major ACPI table used to describe what peripherals the machine has, and information on PCI IRQ mappings and power management.

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DefinitionBlock ("", "DSDT", 2, "", "", 0x0)
{
	Scope (\_SB)
	{
		Device (PCI0)
		{
			Name (INT1, 0x1234)
			Name (_HID, EisaId ("PNP0A08") /* PCI Express Bus */)
			Name (_CID, EisaId ("PNP0A03") /* PCI Bus */)
			Method (^BN00, 0, NotSerialized)
			{
			Return (0x12 + INT1)
			}
			
			Method (_BBN, 0, NotSerialized)
			{
			Return (BN00 ())
			}
			
			Name (_UID, 0x00) // _UID: Unique ID
			
			OperationRegion (MCHT, SystemMemory, 0xFED10000, 0x6000)
			Field (MCHT, ByteAcc, NoLock, Preserve)
			{
				Offset (0x5994),
				RPSL, 8,
				Offset (0x5998), 
				RP0C, 8,
				RP1C, 8,
				RPNC, 8
			}
		}
	}
}

Once a file containing ASL similar to this example is compiled, the file is packaged as firmware. During the initialization of the OS, a namespace hierarchy is created and helps the OS find devices and initialize drivers for them. The following diagram illustrates this concept.

这是我曾经提交过的pr dm:gvt:update bus0 memlimit32 value，该patch与DSDT相关。

参考资料：

  1. Device Model high-level design
  2. ACPI Source Language (ASL) Tutorial