dmi_system_event_log
Synopsis
#include <opendmi/entity/system-event-log.h>
typedef struct dmi_system_event_log {
uint16_t area_length;
uint16_t header_offset;
uint16_t data_offset;
dmi_system_log_access_method_t access_method;
dmi_system_log_status_t status;
uint32_t access_address;
dmi_system_log_io_ports_t access_ports;
uint16_t access_gpnv_handle;
uint32_t change_token;
dmi_system_log_header_format_t header_format;
size_t descriptor_count;
dmi_system_log_type_descriptor_t *descriptors;
} dmi_system_event_log_t;Description
The dmi_system_event_log_t structure holds the decoded system event log
structure (type 15) of SMBIOS. Its presence tells that the system keeps an
event log: a fixed-length area of non-volatile storage, which starts with an
optional header and goes on with event records of variable length. The
structure says where the area lies, how software reaches it, and which kinds
of events the log records. The library does not read the log area itself.
Software can notice new events by reading the structure again from time to
time and comparing change_token with the value it has seen before. When
the table has been read from a copy of the firmware data, status and
change_token may be out of date.
The structure is returned by dmi_entity_info for the structures of type
DMI_TYPE(system_event_log), and lives as long as the context it has been
decoded in.
Fields
area_length-
Length of the log area, in bytes, from the first byte of the header to the last byte of the data.
header_offset-
Offset (or index) of the log header within the non-volatile storage, counted from the access method address. For the access method with a single 8-bit index port, the high byte is 0.
data_offset-
Offset (or index) of the first byte of the log data, counted the same way. The data follows the header directly, so the length of the header is
data_offset - header_offset. access_method-
Method used to reach the log area, see
dmi_system_log_access_method. It also tells howaccess_addressis to be read. status-
Whether the log area is valid and whether it is full, see
dmi_system_log_status. access_address-
Access method address, as stored in the structure. For
DMI_SYSTEM_LOG_ACCESS_METHOD_MMAP_32BIT_ADDR, the 32-bit physical address of the log area; the other access methods are better read throughaccess_portsandaccess_gpnv_handle. access_ports-
Index and data I/O ports of the indexed I/O access methods, see
dmi_system_log_io_ports: the low word ofaccess_addressis the index port, the high word the data port. Filled in whatever the access method is, but only meaningful for the indexed I/O ones. access_gpnv_handle-
Handle of the general-purpose non-volatile data area holding the log, which is the low word of
access_address. Filled in whatever the access method is, but only meaningful forDMI_SYSTEM_LOG_ACCESS_METHOD_DATA_FUNCTIONS. change_token-
Token which the firmware changes every time the log is updated, 0 if the firmware does not implement it.
header_format-
Format of the log header, see
dmi_system_log_header_format. Present since SMBIOS 2.1; for older structures holds 0, which reads asDMI_SYSTEM_LOG_HEADER_FORMAT_NO_HEADER. descriptor_count-
Number of elements of
descriptors: the descriptors the structure holds completely, 0 if it holds none. Present since SMBIOS 2.1; 0 otherwise. descriptors-
Array of the event log types the log supports, each with the format of the variable data of its events, see
dmi_system_log_type_descriptor;nullptrif there are none. Descriptors longer than two bytes are allowed for future extensions, and their extra bytes are skipped. Present since SMBIOS 2.1.
Examples
dmi_registry_t *registry = dmi_get_registry(context);
dmi_entity_t *entity = dmi_registry_lookup_first(registry,
DMI_TYPE(system_event_log), false);
dmi_system_event_log_t *log_info = dmi_entity_info(entity,
DMI_TYPE(system_event_log));
if (log_info != nullptr) {
printf("Log area: %u bytes%s\n", (unsigned)log_info->area_length,
log_info->status.is_log_area_full ? ", full" : "");
for (size_t i = 0; i < log_info->descriptor_count; i++)
printf("Supported event type: 0x%02x\n",
(unsigned)log_info->descriptors[i].type);
}