acpi_ut_checksum
u8 acpi_ut_checksum(u8 *buffer, u32 length);
if (acpi_ut_checksum((u8 *)rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
(acpi_ut_checksum((u8 *)rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
checksum = acpi_ut_checksum((u8 *)table, length);