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GetSystemFirmwareTable function

Retrieves the specified firmware table from the firmware table provider.

Syntax


UINT WINAPI GetSystemFirmwareTable(
  _In_   DWORD FirmwareTableProviderSignature,
  _In_   DWORD FirmwareTableID,
  _Out_  PVOID pFirmwareTableBuffer,
  _In_   DWORD BufferSize
);

Parameters

FirmwareTableProviderSignature [in]

The identifier of the firmware table provider to which the query is to be directed. This parameter can be one of the following values.

ValueMeaning
'ACPI'The ACPI firmware table provider.
'FIRM'The raw firmware table provider.
'RSMB'The raw SMBIOS firmware table provider.

 

FirmwareTableID [in]

The identifier of the firmware table. This identifier is little endian, you must reverse the characters in the string.

For example, FACP is an ACPI provider, as described in the Signature field of the DESCRIPTION_HEADER structure in the ACPI specification (see http://www.acpi.info). Therefore, use 'PCAF' to specify the FACP table, as shown in the following example:

retVal = GetSystemFirmwareTable('ACPI', 'PCAF', pBuffer, BUFSIZE);

For more information, see the Remarks section of the EnumSystemFirmwareTables function.

pFirmwareTableBuffer [out]

A pointer to a buffer that receives the requested firmware table. If this parameter is NULL, the return value is the required buffer size.

For more information on the contents of this buffer, see the Remarks section.

BufferSize [in]

The size of the pFirmwareTableBuffer buffer, in bytes.

Return value

If the function succeeds, the return value is the number of bytes written to the buffer. This value will always be less than or equal to BufferSize.

If the function fails because the buffer is not large enough, the return value is the required buffer size, in bytes. This value is always greater than BufferSize.

If the function fails for any other reason, the return value is zero. To get extended error information, call GetLastError.

Remarks

As of Windows Server 2003 with Service Pack 1 (SP1), applications cannot access the \Device\PhysicalMemory object. Access to this object is limited to kernel-mode drivers. This change affects applications read System Management BIOS (SMBIOS) or other BIOS data stored in the lowest 1MB of physical memory. Applications have the following alternatives to read data from low physical memory:

  • Retrieve the SMBIOS properties using WMI. Many individual properties are contained in the Win32 classes. You can also retrieve the raw SMBIOS data in a single buffer using the MSSMBios_RawSMBiosTables class.
  • Use the GetSystemFirmwareTable function to read the raw SMBIOS firmware table.

There is no way for applications to write to low physical memory.

The raw SMBIOS table provider ('RSMB') retrieves the contents of the raw SMBIOS firmware table. The pFirmwareTableBuffer buffer receives the following data:


#include <windows.h>

struct RawSMBIOSData
{
    BYTE    Used20CallingMethod;
    BYTE    SMBIOSMajorVersion;
    BYTE    SMBIOSMinorVersion;
    BYTE    DmiRevision;
    DWORD    Length;
    BYTE    SMBIOSTableData[];
};

The raw firmware table provider ('FIRM') retrieves the contents of the specified physical address range. The function returns the size of the address range.

The ACPI table provider ('ACPI') retrieves the contents of the specified ACPI table. Because OEMs can include ACPI firmware tables that are not listed in the ACPI specification, you should first call EnumSystemFirmwareTables to enumerate all ACPI tables that are currently on the system.

For ACPI, if the system contains multiple tables with the same name, they are all enumerated with EnumSystemFirmwareTables. However, GetSystemFirmwareTable retrieves only the first table in the list with this name.

Requirements

Minimum supported client

Windows Vista, Windows XP Professional x64 Edition [desktop apps only]

Minimum supported server

Windows Server 2008, Windows Server 2003 with SP1 [desktop apps only]

Header

Winbase.h (include Windows.h)

Library

Kernel32.lib

DLL

Kernel32.dll

See also

EnumSystemFirmwareTables
System Information Functions