Linux kernel will use 64bit address if it is available as below:
/*******************************************************************************
*
* FUNCTION: acpi_tb_select_address
*
* PARAMETERS: register_name - ASCII name of the ACPI register
* address32 - 32-bit address of the register
* address64 - 64-bit address of the register
*
* RETURN: The resolved 64-bit address
*
* DESCRIPTION: Select between 32-bit and 64-bit versions of addresses within
* the FADT. Used for the FACS and DSDT addresses.
*
* NOTES:
*
* Check for FACS and DSDT address mismatches. An address mismatch between
* the 32-bit and 64-bit address fields (FIRMWARE_CTRL/X_FIRMWARE_CTRL and
* DSDT/X_DSDT) could be a corrupted address field or it might indicate
* the presence of two FACS or two DSDT tables.
*
* November 2013:
* By default, as per the ACPICA specification, a valid 64-bit address is
* used regardless of the value of the 32-bit address. However, this
* behavior can be overridden via the acpi_gbl_use32_bit_fadt_addresses flag.
*
******************************************************************************/
static u64
acpi_tb_select_address(char *register_name, u32 address32, u64 address64)
{
if (!address64) {
/* 64-bit address is zero, use 32-bit address */
return ((u64)address32);
}
if (address32 && (address64 != (u64)address32)) {
/* Address mismatch between 32-bit and 64-bit versions
*/
ACPI_BIOS_WARNING((AE_INFO,
"32/64X %s address mismatch in FADT: "
"0x%8.8X/0x%8.8X%8.8X, using %u-bit address",
register_name, address32,
ACPI_FORMAT_UINT64(address64),
acpi_gbl_use32_bit_fadt_addresses ? 32 :
64));
/* 32-bit address override */
if (acpi_gbl_use32_bit_fadt_addresses) {
return ((u64)address32);
}
}
/* Default is to use the 64-bit address */
retur
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https://bugs.launchpad.net/bugs/1286965
Title:
[Dell Precision T7600] HIGH failures in FWTS report
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