This page lists known issues with silicon (hardware) errata of 3rd-party parts (micro controller, sensors, etc.) used on the Pixhawk board series. Depending on the type of silicon error, these cannot be fixed in software and might impose specific limitations.
FMUv2 / Pixhawk Silicon Errata
Flash Bank 2 and full speed USB device exclusive.
Silicon revisions up to rev 2 (revision 3 is the first not affected) can produce errors / data corruption when accessing the 2nd flash bank while there is activity on PA12, which is one of the USB data lines. There is no workaround / software fix for this, except to not use the flash bank #2. Since USB is needed to program the device, Pixhawk revisions built with silicon revisions < rev 3 can only use up to 1MB of the 2MB flash of the microprocessor.
The errata is fixed in later versions, but this may not be detected if you are using an older bootloader. See Bootloader Update for more information.
FMUv1 / Pixhawk Silicon Errata
No known issues.