the code that generates the MCE log contained a typo that appeared in several places. Consequently, mcelog would ignore a chunk of the data at the beginning of each record. The chunk of data would be so large that each record would be empty and therefore, the log itself would be empty. With this typo corrected, mcelog correctly generates its log of MCE events. (BZ#501512)

mcelog is unable to obtain MCE data from paravirtualized Xen guests on a system. Previously, each time that mcelog tried and failed to obtain this data, it would generate an error report -- by default, once per hour. These error reports could mislead users to think that there was a problem with their system. Now, mcelog does not generate error reports when it cannot obtain MCE data from paravirtualized Xen guests, and therefore avoids any potential confusion. (BZ#511126)

the mcelog package had not been updated in several releases. Therefore, the existing package could not decode MCE events from newer Intel processors such as the "Nehalem" and "Dunnington" series. This update adds support for newer Intel hardware. (BZ#473392)