edac (3)

#include <edac.h>

cc ... -ledac

edac_handle * edac_handle_create (void);

void edac_handle_destroy (edac_handle *edac);

int edac_handle_init (edac_handle *edac);

unsigned int edac_mc_count (edac_handle *edac);

int edac_handle_reset (edac_handle *edac);

int edac_error_totals (edac_handle *edac, struct edac_totals *totals);

edac_mc * edac_next_mc (edac_handle *edac);

int edac_mc_get_info (edac_mc *mc, struct edac_mc_info *info);

edac_mc *edac_next_mc_info (edac_handle *edac,
                            struct edac_mc_info *info);

int edac_mc_reset (struct edac_mc *mc);

edac_csrow * edac_next_csrow (struct edac_mc *mc);

int edac_csrow_get_info (edac_csrow *csrow,
                         struct edac_csrow_info *info);

edac_csrow * edac_next_csrow_info (edac_mc *mc,
                                   struct edac_csrow_info *info);

const char * edac_strerror (edac_handle *edac);

edac_for_each_mc_info (edac_handle *edac, edac_mc *mc,
                       struct edac_csrow_info *info)    { ... }

edac_for_each_csrow_info (edac_mc *mc, edac_csrow *csrow,
                          struct edac_csrow_info *info) { ... }

The libedac library offers a very simple programming interface to the information exported from in-kernel EDAC (Error Detection and Correction) drivers in sysfs. The edac-util(8) utility uses libedac to report errors in a user-friendly manner from the command line.

EDAC errors for most systems are recorded in sysfs on a per memory controller (MC) basis. Memory controllers are further subdivided by csrow and channel. The libedac library provides a method to loop through multiple MCs, and their corresponding csrows, obtaining information about each component from sysfs along the way. There is also a simple single call to retrieve the total error counts for a given machine.

In order to use libedac an edac_handle must first be opened via the call edac_handle_create(). Once the handle is created, sysfs data can be loaded into the handle with edac_handle_init(). A final call to edac_handle_destroy() will free all memory and open files associated with the edac handle.

edac_handle_create() will return NULL on failure to allocate memory.

The edac_strerror function will return a descriptive string representation of the last error for the libedac handle edac.

The edac_error_totals() function will return the total counts of memory and pci errors in the totals structure passed to the function. The totals structure is of type edac_totals which has the form:

struct edac_totals {
   unsigned int  ce_total;         /* Total corrected errors   */
   unsigned int  ue_total;         /* Total uncorrected errors */
   unsigned int  pci_parity_total; /* Total PCI Parity errors  */
};

Systems may have one or more memory controllers (MCs) with EDAC information. The number of MCs detected by EDAC drivers may be queried with the edac_mc_count() function, while the edac_next_mc function will return a handle to the next memory controller in the libedac handle\'s internal list. This memory controller is represented by the opaque edac_mc type.

edac_next_mc will return NULL when there are no further memory controllers to return. Thus the following example code is another method to count all EDAC MCs (assuming the EDAC library handle edac has already been initialized):

int i = 0;
edac_mc *mc;
while ((mc = edac_next_mc (edac)))
    i++;
return (i);

To query information about an edac_mc, use the edac_mc_get_info function. This function fills in the given info structure, which is of type edac_mc_info:

struct edac_mc_info {
    char           id[];           /* Id of memory controller */
    char           mc_name[];      /* Name of MC              */
    unsigned int   size_mb;        /* Amount of RAM in MB     */
    unsigned int   ce_count;       /* Corrected error count   */
    unsigned int   ce_noinfo_count;/* noinfo Corrected errors */
    unsigned int   ue_count;       /* Uncorrected error count */
    unsigned int   ue_noinfo_count;/* noinfo Uncorrected errors*/
};

The function edac_next_mc_info() can be used to loop through all EDAC memory controllers and obtain MC information in a single call. It is a combined edac_next_mc() and edac_mc_get_info().

The function edac_handle_reset() will reset the internal memory controller iterator in the libedac handle. A subsequent call to edac_next_mc() would thus return the first EDAC MC.

A convenience macro, edac_for_each_mc_info(), is provided which defines a for loop that iterates through all memory controller objects for a given EDAC handle, returning the MC information in the info structure on each iteration. For example (assuming initialized libedac handle edac):

edac_mc *mc;
struct edac_mc_info info;
int count = 0;

edac_for_each_mc_info (edac, mc, info) {
    count++;
    printf ("MC info: id=%s name=%s\n", info.id, info.mc_name);
}

Each EDAC memory controller may have one or more csrows associated with it. Similar to the MC iterator functions described above, the edac_next_csrow() function allows libedac users to loop through all csrows within a given MC. Once the last csrow is reached, the function will return NULL.

The edac_csrow_get_info() function returns information about edac_csrow in the edac_csrow_info structure, which has the contents:

struct edac_csrow_info {
    char          id[];      /* CSROW Identity (e.g. csrow0)  */
    unsigned int  size_mb;   /* CSROW size in MB              */
    unsigned int  ce_count;  /* Total corrected errors        */
    unsigned int  ue_count;  /* Total uncorrected errors      */
    struct edac_channel channel[EDAC_MAX_CHANNELS];
};

struct edac_channel {
    int           valid;            /* Is this channel valid */
    unsigned int  ce_count;         /* Corrected error count */
    int           dimm_label_valid; /* Is DIMM label valid?  */
    char          dimm_label[];     /* DIMM name             */
};

The edac_next_csrow_info() function is a combined version of edac_next_csrow() and edac_csrow_get_info() for convenience.

The edac_mc_reset() function is provided to reset the edac_mc internal csrow iterator.

A convenience macro, edac_for_each_csrow_info(), is provided which defines a for loop that iterates through all csrow objects in an EDAC memory controller, returning the csrow information in the info structure on each iteration.

Initialize libedac handle:

edac_handle *edac;

if (!(edac = edac_handle_create ())) {
    fprintf (stderr, "edac_handle_create: Out of memory!\n");
    exit (1);
}

if (edac_handle_init (edac) < 0) {
   fprintf (stderr, "Unable to get EDAC data: %s\n",
                    edac_strerror (edac));
   exit (1);
}

printf ("EDAC initialized with %d MCs\n", edac_mc_count (edac));

edac_handle_destroy (edac);

Report all DIMM labels for MC:csrow:channel combinations

edac_mc *mc;
edac_csrow *csrow;
struct edac_mc_info mci;
struct edac_csrow_info csi;

edac_for_each_mc_info (ctx->edac, mc, mci) {
    edac_for_each_csrow_info (mc, csrow, csi) {
        char *label[2] = { "unset", "unset" };

        if (csi.channel[0].dimm_label_valid)
            label[0] = csi.channel[0].dimm_label;
        if (csi.channel[1].dimm_label_valid)
            label[1] = csi.channel[1].dimm_label;

        printf ("%s:%s:ch0 = %s\n", mci.id, csi.id, label[0]);
        printf ("%s:%s:ch1 = %s\n", mci.id, csi.id, label[1]);
    }
}

edac-util(8), edac-ctl(8)