Can anyone please tell me what information is present in the acpi tables ?
There's plenty of information out there on the subject. Have you tried Google?
If you need detailed information, you need to read the ACPI Specification Rev 4 which is available at www.acpi.info
Advanced Configuration and Power Interface(ACPI)
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ACPI support provide numerous tables of data describing a computer's
configuration and power management capabilities. -
ACPI aims to consolidate and improve upon existing power and configuration standards for hardware devices.
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ACPI contains definition blocks that describe all the hardware
that can be managed through ACPI. -
These definition blocks include both data and machine-independent byte-code that is used to perform hardware management operations.
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ACPI was designed to enable the operating system to set up and control the individual hardware components.
If you want to see the output of the ACPI tables refer the following link.
View your motherboard's ACPI tables (in Debian & Ubuntu) | commandlinefu.com